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Examining the Evidence Against Steven Avery: A Preliminary Forensic Analysis

By Jennifer Bucholtz, Faculty Member, Criminal Justice and Forensic Science at American Military University

In recent weeks, Americans have become enthralled with the Netflix series, “Making a Murderer.” The 10-part documentary examines the story of Steven Avery and Brendan Dassey, both imprisoned for the murder of Teresa Halbach. Halbach was killed in 2005 in Manitowac, Wisconsin, and several pieces of evidence associated with her were found on Avery’s property.

During their trials, the Manitowac County Sheriff’s Department presented several key pieces of evidence against Steven Avery, proving, they said, beyond a reasonable doubt that Avery murdered Halbach with the help of Dassey, his nephew and next-door neighbor.

After watching the documentary, I, like many others, felt Avery and Dassey had been subjected to a biased trial and wrongly imprisoned. However, as I read through the hundreds of pages of transcripts and examined the evidence against Steven Avery, a clearer picture of the murder took shape.

As an instructor of forensic sciences, I conducted days of research on the forensic evidence against Steven Avery and examined its relevance and validity. The court transcripts from Avery’s trial just became available; I have only begun to digest the thousands of pages they comprise. However, those from his alleged co-conspirator, Brendan Dassey, were already readily available when I began my research. Therefore, the analysis I used is based on the Dassey trial transcripts, interviews and interrogations of Dassey by the police, information in the Netflix documentary, and open-source information available on the Internet. I will not address other anecdotes or testimonials from this case.

The forensic evidence against Steven Avery included:

  • Halbach’s blood in her vehicle
  • A spent bullet with Halbach’s DNA on it
  • Avery possessed a key to her vehicle
  • Avery’s blood inside Halbach’s vehicle
  • The burnt remains of Halbach’s body on Avery’s property

The Prosecution’s Description of the Crime

The synopsis presented by the prosecution is:

Halbach came to Avery’s house on the afternoon of October 31, 2005, to photograph a vehicle he had for sale and wanted listed in Auto Trader magazine, where Halbach worked as a photographer. Avery allegedly lured Halbach into his house where he tied her to his bed, assaulted and stabbed her. He then moved her body to his garage, where he shot her to death. Following the shooting, he burned her body as well as her personal belongings in his outdoor burn pit, in an attempt to cover up the crime. At some point, he removed the license plates from her vehicle, a 1999 Toyota RAV4, and attempted to hide the car in a distant area of his 40-acre property. After hiding it, he opened the hood and disconnected the battery terminals so the vehicle would not start. At some point during these events, Avery cut the middle finger on his right hand.

The Defense’s Version of Events

During the trial, Avery’s defense team maintained the Manitowac Sheriff’s Department set up their client. According to his lawyers, several law enforcement officials, upset with their names being tarnished due to the previous false conviction of Avery, wanted retribution. The defense stated they did not believe Manitowac authorities killed Teresa. Rather, they felt someone else did, but that law enforcement planted evidence against Steven Avery (including his blood in Halbach’s car, her DNA on the spent bullet in the garage, her charred remains on his property, and her car key in his bedroom), in order to obtain an arrest warrant, and the subsequent conviction of Avery.

Examining the Forensic Evidence Against Steven Avery

Evidence Against Steven Avery: Halbach's blood found in her trunk
Halbach’s blood found in her trunk

Halbach’s Blood in Her Vehicle

Several blood stains, positively identified as Halbach’s, were found in the rear cargo area of her vehicle. Forensic analysts testified that at least one of the stains had come from her bloody hair, which could have happened when her killer placed her in the back of the vehicle.

Spent Bullet
One spent .22 caliber bullet was found inside Avery’s garage under a portable air compressor. Currently, there is only one photo available of this bullet, which was taken from directly above it.

Evidence Against Steven Avery: Bullet found in Avery's garage
Bullet found in Avery’s garage

No side view of the bullet has been released publicly. Therefore, any damage to the bullet cannot be analyzed at this time. This bullet was positively linked to a rifle found in Avery’s house, meaning it was fired from his rifle. The bullet reportedly had Halbach’s DNA on it – but this evidence should not have been admissible in court because the control sample (not the DNA sample from the bullet) was contaminated by the forensic analyst. Despite the contamination deeming the evidence inadmissible, a one-time exception to the rule was filed by the analyst and granted by the court.

Two skull fragments belonging to Halbach were found in Avery’s burn pit. Both showed evidence of “beveling” on the inner side of the skull portions, which can result from being penetrated by a bullet. It can also be caused by blunt force trauma, such as being hit with a hammer.

If Halbach was shot multiple times in the head in Avery’s garage, there should be evidence of high-velocity blood splatter. The absence of blood evidence in the garage suggests she might have been shot elsewhere or not shot at all.

Halbach’s Car Key
A key to Halbach’s Toyota RAV4 was found in a bedroom in Avery’s house. This is the most questionable piece of evidence against Steven Avery introduced at trial. Much controversy surrounds this discovery as the first two times investigators

Evidence Against Steven Avery: Halbach's car key found in Avery's home
Halbach’s car key found in Avery’s home

examined the bedroom, they saw no key. On the third search, the key was found nearly in plain sight, next to this bookcase. Investigators assert that the key was hidden, by Avery, in the bookcase and it fell out while they were examining the other contents of that piece of furniture.

Forensic analysts testified that only Avery’s DNA was found on the key and key chain. This is surprising: If Halbach used the key on a regular basis, there should have been some evidence of her DNA on the key. It may or may not be important that the key found was either the “valet” key to her vehicle or an after-market spare, not its primary key. This is based on the shape of the head of the key and verified by the handbook provided by Toyota for her particular vehicle. She may have lost the main key for her car or used the valet key for some other reason.

Avery’s Blood in Halbach’s Car
Steven Avery’s blood was positively identified at six locations throughout Halbach’s car. These locations include to the right of the ignition, on both front seats, on a CD case and near the front passenger seat. It is known that Avery had a cut on his right middle finger when police questioned him on

Evidence Against Steven Avery: Avery's blood found in Halbach's vehicle
Avery’s blood found in Halbach’s vehicle

November 5, 2005. Much debate has occurred over how Avery’s blood was found in the vehicle, but none of his fingerprints were. I postulate that he was wearing gloves either during the murder or while picking up debris to burn in the fire, but unknowingly cut himself through the glove. This would have allowed blood to escape without leaving fingerprints.

Remains of Bones in the Fire Pit

Evidence Against Steven Avery: Halbach's bones after being burned
Halbach’s bones after being burned

Hundreds of fragments of Halbach’s bones were found in a burn pit approximately 20 feet behind Avery’s garage. Her bones were intertwined with the steel cables from several car tires, evidence used by specially trained arson investigators and an anthropologist to back up their testimony at Dassey’s trial that, in their expert opinions, Halbach’s body was burned in the fire pit in which it was found.

The defense postulated that her body was burned elsewhere and transported back to the fire pit next to Avery’s house in order to frame him. However, the distribution of bones and ashes suggests otherwise. If the burned remains of her body had been somehow transported to Avery’s pit, they would have been more haphazardly dispersed when found.

A Hypotheses of the Murder

Based on the forensic evidence against Steven Avery, one theory of what happened on October 31, 2005 formed in my mind. Avery may have lured Halbach into his home under the guise of needing to pay her. A confrontation of some sort occurred or Avery simply took his victim by surprise when her back was turned. Avery may have hit her in the head with something, rendering her unconscious. This blunt force trauma could have resulted in a bleeding head wound, which led to her having blood in her hair. With her unconscious, Avery may have placed her on his bed and sexually assaulted her and/or stabbed her, as alleged by the prosecution based on information provided by Dassey (which he later recanted). There is no evidence against Steven Avery of a sexual assault, however, because Halbach’s body was burned to a point where no foreign DNA could be extracted.

To remove her from the house, Avery may have wrapped up Halbach’s body in the comforter from his bed. When police conducted their search of his house, the bed was absent of any sheets, pillow cases or a comforter. Carrying her out of the house in the comforter would have served at least two purposes for Avery:

  1. If she were bleeding on the comforter, it would absorb the blood and potentially not leave blood on his bed.
  2. The comforter would disguise the body as he carried it out of the house, in case anyone saw him exiting the house with her.

A normal bedding set includes a comforter, top sheet, fitted sheet and mattress pad, which could potentially be enough layers to absorb the blood if she were moved from the bed shortly after being hit in the head (or possibly stabbed as alleged by the prosecution). There is a possibility Avery carried her body out of his house during hours of daylight and placed her body in the back of her vehicle, moving the vehicle into his garage to conceal it from passersby. Teresa weighed approximately 135 pounds and Avery may have had difficulty carrying her body, resulting in him placing the body in the rear of the vehicle in order to move it into his garage. This would account for her blood being found in the rear cargo area of her vehicle. Reportedly, the comforter from Avery’s bed was burned (according to Dassey), leaving no trace of it or any blood that might have been on it.

Once in the garage, Avery allegedly removed Halbach’s body from the vehicle in his garage and shot her several times. He may have covered her head with a portion of the comforter to make the act psychologically easier for him. If this were the case, the comforter could have absorbed a majority of the blood splatter that should have been deposited inside the garage. The bullets still would have likely created holes in the blanket, causing some blood to leak through. Luminol tests of the garage showed multiple areas of blood that had been cleaned up, though those blood stains could not be identified as Halbach’s. The use of oxygen bleach (versus chlorine bleach) will degrade DNA to a point where it cannot be identified as belonging to a particular person. Oxygen bleach is a common household cleaning agent. Only Avery’s DNA was found in the garage, but it was a place he frequented and it follows that his DNA should be there.

After the killing, Avery likely moved Halbach’s body to the fire pit. He then gathered up tires, an old bench seat out of a van, pieces of wood and other random items. He used these items to start and maintain a large bonfire for several hours, during which Halbach’s body was destroyed. He used a shovel, found by the fire pit, to stir the fire, resulting in the complete burning and breakage of Halbach’s bones. The arson investigator who testified in court found that based on the burn patterns of the bones, it appeared that the fire pit was the location where the body was burned.

At some point during the evening, Avery placed Halbach’s personal items, including her camera, cell phone, PalmPilot and purse into a nearby burn barrel, attempting to dispose of this evidence as well. Remains of a camera and a cell phone made by the same companies as those Halbach owned were recovered by investigators.

Later, Avery drove Halbach’s car to the opposite end of his salvage yard from where he lived and attempted to conceal it with branches and other car parts. It was during this time that his own blood seeped through the glove he was wearing, leaving transfer stains in six places in her car. He also opened the hood and disconnected the battery, leaving his DNA on the hood latch.

The prosecution indicated this DNA was from Avery’s sweat; however, the sample was small enough that it could have been from his blood. Avery probably kept the car key, in case he had the opportunity to move the vehicle farther away from his lot at a later date or place it in the car crusher located nearby. He may have cleaned the key and key chain, accidentally leaving only his DNA on it, then stashed it in the bookcase in the bedroom.

Was Avery Framed?

To this day, Avery maintains he was framed by the Manitowac Sheriff’s Department. Due to a previous false conviction for rape in 1985, Avery was awarded $400,000 by the department. The false arrest and imprisonment resulted in a black eye for many employees in the local criminal justice system. He feels this bad publicity led them to framing him for Halbach’s murder, specifically by planting his blood in her vehicle, a bullet in his garage, and her car key in his bedroom.

Avery used the compensation from the previous case to hire two prominent lawyers to defend him from the 2005 murder charge. Avery’s defense insinuated someone on the investigative team planted the key. Any scenario is a possibility; however, this theory would indicate that the person who planted the key, the bullet and Avery’s blood was involved in Halbach’s death.

It is hard to conceive and highly unlikely that several law enforcement officers would be willing to engage in a murder and subsequent cover-up. Alternatively, they may have felt there was enough circumstantial evidence implicating Avery in her death, but wanted to ensure he was convicted. In order to do this, they must have had access to her car key in order to plant it in his home.

Though there were some mistakes made by the law enforcement officials in this case (a topic for another article), the evidence against Steven Avery, whether circumstantial or not, overwhelmingly points to him as the perpetrator. So far, there has been no proof that anyone else had the same access to Halbach herself and Avery’s property on the day she was killed. Also, Avery has no alibi for the time frame when the murder occurred. Remember, in order to obtain a conviction, the prosecution only has to prove a case “beyond a reasonable doubt.” They do not have to show with 100 percent certainty that someone committed a crime.

Could Evidence Against Steven Avery Been Planted?

As shown in the documentary, lawyers for Avery initially believed they could prove his blood was planted. A vial with Avery’s blood, collected in connection with the 1985 rape trial, was in the sheriff’s department’s evidence storage. The evidence tape on the container holding this vial had been cut and taped back together with scotch tape. The vial itself had a needle-sized hole in the top. First impressions were that someone extracted blood from that vial and planted it in Halbach’s car.

Evidence Against Steven Avery: Punctured vial with Avery's blood sample
Punctured vial with Avery’s blood sample

It is known now that that vial was a “Vacu-tainer,” which requires a needle to be inserted in the top while the person’s blood is being transferred into it. This accounts for the needle hole on top. Additionally, the nurse who collected the blood from Avery signed a statement that she put the hole in the top of the tube. Unfortunately, the nurse is now deceased and cannot further comment on the details.

Chain of custody records show that the evidence container was opened by Avery’s previous defense team (who represented him in his 1985 trial for rape) on June 19, 2002. The container was opened in order to extract evidence for comparison purposes, which ultimately cleared him of the rape. Of course, this does not eliminate the possibility that another person did illegally access the blood vial at some point and remove blood from it, but at least there is a legitimate documented reason why it was opened.

Furthermore, the Vacu-tainer with his blood contained EDTA, an anti-coagulant that keeps a blood sample in liquid form. The FBI tested the blood samples found in Halbach’s car for the presence of EDTA but returned a negative result. This negative result does not mean that there was no EDTA present in the blood in the car, it simply means that if there was EDTA, the presence of it was too minute for the FBI to detect.

Some Final Considerations

Based on his previous false imprisonment and subsequent release due to improvements in DNA analysis, Avery knew how important DNA was to a case. His knowledge may have led him to try to eliminate all DNA evidence, believing that without it, the prosecution would not be able to prove their case. He also had five entire days (from when Halbach went missing to when her vehicle was discovered) to clean his house, garage, and property of any DNA evidence linking him to the murder.

If Avery was not the one who murdered and burnt Halbach’s body, it seems logical he would have immediately spoken up about the sudden appearance of a large amount of burnt materials right outside his house. Witnesses report seeing a bonfire on October 31, 2005, the evening Halbach went missing. If someone besides Avery made and (for several hours) tended to the fire right outside his house, he should have known who that was and reported it later to the police.

Though most of the evidence against Steven Avery is circumstantial, it all points to the same person as the killer, although it does not make it a solid open-and-shut case. But, based on the jury’s decision, it did provide proof “beyond a reasonable doubt” that Avery committed the crime.

I have to admit my conclusions based on the evidence were disappointing. I hoped to refute the evidence against Steven Avery presented in this case or at least find an indication that pointed to a different perpetrator. Like many, I do not want to believe a person falsely imprisoned for 18 years would go on to commit a horrific crime. But, without some new evidence, I am forced to believe Avery is responsible.

Jennifer BucholtzAbout The Author: Jennifer Bucholtz is a former U.S. Army Counterintelligence Agent and a decorated veteran of the Iraq and Afghanistan wars. She holds a Bachelor of Science in criminal justice, Master of Arts in Criminal Justice and Master of Science in Forensic Sciences. Jennifer has an extensive background in U.S. military and Department of Defense counterintelligence operations. While on active duty, she served as the Special Agent in Charge for her unit in South Korea and Assistant Special Agent in Charge at stateside duty stations. Jennifer has also worked for the Arizona Department of Corrections and Office of the Chief Medical Examiner in New York City. Jennifer is currently an adjunct faculty member at American Military University and teaches courses in criminal justice and forensic sciences. You can contact her at


Leischen Kranick is a Managing Editor at AMU Edge. She has 15 years of experience writing articles and producing podcasts on topics relevant to law enforcement, fire services, emergency management, private security, and national security.

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