AMU Careers Careers & Learning Law Enforcement Public Safety Public Service

Veteran Forensic Scientist Examines Negligence in the Collection of Evidence Against Amanda Knox

By Dena Weiss, professor of criminal justice at American Military University

Meredith Kercher was found brutally murdered on November 2, 2007 in Perugia, Italy. This young 22-year-old British exchange student from the University of Foreigners was found stabbed and posed in a provocative manner in her bedroom located in a cottage shared by three other roommates. Two of the roommates were older Italian women who were several years older then Kercher and were employed, not students at the university. The remaining roommate, Amanda Knox, was a 21-year old exchange student from Seattle, Washington.

Soon after the homicide, Amanda Knox was arrested along with two other individuals, charged and sentenced in 2009 to 26 years for the murder. In 2011, an appeals court overturned the conviction and Knox returned home to the United States. In 2013, the higher court of Italy reversed the appeals court’s decision and ordered a retrial.

In January 2014, the Italian court reinstated the murder conviction sentencing her to 28 ½ years in an Italian prison.

No murder weapon was found and although the crime scene contained a plethora of DNA evidence, not a trace of Knox was found in the victim’s bedroom where the homicide occurred. The following account of the days leading up to the trial will provide a prime example of illegal investigative and interrogation techniques, poor evidence collection, packaging and storage, as well as unacceptable forensic analysis and testimony.

Who Is Amanda Knox?
Knox arrived in Perugia to study at the University of Foreigners with little comprehension of the Italian language even though she majored in Italian at the University of Washington (Rich, 2011). Growing up in Seattle she was a smart student but naïve to the ways of the world. She was often described as eager to help a stranger and threw caution to the wind when it came to public interaction. Knox discovered a small cottage close to the University and moved in with three other roommates. Although she seemed to get along with Kercher more than her other two older roommates, Kercher’s mother claimed that Kercher complained that Knox was a slob and irritated her with loud singing and ridiculous behavior (Rich, 2011). Before long, Knox met a 23-year old young man studying computer science named Raffaele Sollecito. Along with school and spending her time with Sollecito, Knox worked as a waitress in a bar called Le Chic. The night of the murder, she had been scheduled to work but was contacted by the bar owner, Patrick Lumumba, and informed there was no need to work that evening due to the slow (Rich, 2011).

Murder in Perugia
November 1 is referred to as All Saints Day in Italy and is a work holiday for most citizens. November 2 is considered a Holy Day where dead relatives are celebrated with feasts and gifts (Latto, 2007). Since Amanda Knox was released from work on All Saints Day, she spent the night with Sollecito at his apartment. The apartment had a plumbing problem that resulted in leaking pipes every time the kitchen sink was used.

After the two had prepared dinner the evening of November 1st, there were puddles of water on the floor. Sollecito did not own a mop so the two retired for the evening planning to clean the mess up the next morning. Knox returned to her cottage at 10:30 a.m. to take a shower and retrieve a mop. When she arrived, she noticed the front door was open which was odd because she knew Kercher was the only roommate in town for the weekend.

Upon entering the residence Amanda noticed Kercher’s bedroom door was closed so she assumed she was asleep and quietly went and showered. When she exited the shower, she noticed blood on the sink. Puzzled, she attempted to figure out if it was coming from her but noticed it was dry. She also noticed feces in the toilet which oddly enough worried her more then the open door or blood and she rushed back to Sollecito’s apartment with the mop.

Knox phoned her other roommates and returned to the cottage with Sollecito where on closer inspection they found a broken window in roommate Filomena Ramanelli’s room. Knocking on Kercher’s bedroom door elicited no response so they phoned the Italian police. For some unknown reason the postal police arrived rather than the Italian military police along with Ramanelli and Ramanelli’s boyfriend. Postal police only respond to misdemeanor crimes and have no experience in violent crimes (Rich, 2011).

At this point, the scene was severely contaminated. Not only had the two roommates and their boyfriend’s entered the crime scene but two postal inspectors. They proceeded to breakdown the door to Kercher’s room where she was found stabbed and naked from the waist down.

Arrested for Murder
Over the next few days Knox and Sollecito were repeatedly called down to the police station and questioned. By November 5, authorities began to get desperate and began a much more unethical series of interrogations which resulted in both questioning their memory and changing their story. Sollecito claimed that it would have been possible for Knox to have left his apartment in the middle of the night without him knowing it. Knox stated she had a vision in her head that involved her boss at work, Patrick Lumumba, killing Kercher and Knox witnessing it with her hands over her ears screaming.

Knox claims the interrogators actually hit her in the back of the head that night and were verbally abusive. Repeated requests for a lawyer and independent translator were denied. Totally exhausted by the middle of the night on November 6, Knox signed two statements indicting her involvement in the crime and was arrested and jailed. Sollecito was also arrested and jailed. Authorities arrested Lumumba as well and took two weeks to release him based on a rock solid alibi.

Evidence Collection
Kercher was found on her back naked from the waist down, her shirt pulled up, and a pillow propped up under her hips. A comforter was lying over her body.  Her injuries included bruises on both sides of her face, several superficial cuts on her hands, arms, and face, and a three-inch fatal wound to her neck (Hendry, 2011).

Amanda Knox case
Evidence from Meredith Kercher’s room. More crime scene pictures can be found at:

The crime scene was Kercher’s bedroom where she appeared to have been sitting on her bed when the attack first commenced. There were blood drops on the floor and the slats of the bed where the mattress had been slightly moved. She appears to have been stabbed on the bed but struggled to the other side of the room where her desk was located. Forcibly removed hair, shoe prints in blood, and blood drops were located by the desk chair. The door to the wardrobe next to the desk had aspirated blood on the front of it and there were blood smears on the floor in front of the wardrobe. Kercher’s bloody fingerprints were on the inside of the wardrobe wall as well, indicating a last attempt to rise from the floor. Drag marks were in the center of the room indicating the killer had dragged her away from the wardrobe and desk area (Hendry, 2011).

The clothing found at the scene exhibited forensic evidence including an inside-out jacket that appeared to have been pulled off of the victim, a t-shirt, sweatshirt, a pair of bloody boots, and a bra with broken straps containing aspirated blood. Clothing was strewn everywhere, drawers were emptied, and, however, all her jewelry was still present in both Romanelli’s room and Kercher’s room. The items that appeared stolen from Kercher were her house keys, two cell phones, two credit cards, and some cash (Burleigh, 2011). Along with the broken window in Romanelli’s room, was a rock on the floor in Romanelli’s room, and blood in several areas of the bathroom shared by Kercher and Knox.

Forensic Evidence Analysis
The police processed the crime scene by dusting with fingerprint powder to reveal fingerprints. Of the numerous fingerprints found at the scene, only one print on a water glass in the kitchen was identified as Amanda’s print. Fourteen of the prints were not identified to anyone involved in the case. A key piece of evidence was a bloody palm print found on the pillow under the victim. This was identified as belonging to Rudy Guede, a black immigrant with a history of petty theft and break-ins who often was seen partying with local college students and who had recently met Kercher at a party thrown by basement occupants of the cottage where Knox and Kercher lived (Sayahg, 2010).

There were numerous bloody shoe and footprints analyzed from the scene due to the apparent struggle during the attack. Five Nike shoe prints were found in blood around the body and leading out the front door and one bloody barefoot imprint on the bathmat in the shared bathroom. The shoeprints in Kercher’s bedroom and leading outside the front door were identified as belonging to Guede. Enormous amounts of blood at the scene and tracked throughout the residence resulted in extensive DNA analysis being conducted. Results showed Guede’s DNA mixed with Meredith’s blood on her purse, on her sweatshirt, in excrement found in the toilet of the bathroom shared by Knox and Kercher, as well as inside Kercher’s body. Although not identified as seminal DNA, epithelial cells known as Touch DNA were found inside Meredith’s vagina (Burleigh, 2011).

A cooking knife collected from the drawer in Sollecito’s kitchen was found to contain minute samples of DNA from Knox. Knox’s DNA was also mixed with DNA samples of Meredith’s blood found on the sink in the bathroom the two shared. A broken bra clip found in Kercher’s bedroom collected six weeks after the murder was identified by the Italian forensic expert Patrizia Stefanoni as containing minute samples of DNA traced back to Sollecito (Waterbury, 2011).

Gross Negligence
The crime scene was compromised as soon as the police arrived. Several individuals tried to open Kercher’s door and two officers entered the room without proper clothing and gloves to prevent contamination. Later evaluation of a video taken during processing of the crime scene proved items such as the bloody boots and purse had been moved, items had been shoved around creating new bloodstains, and the blanket had been removed from the victim without gloves. It was also later determined that investigators moved the nightstand by the bed covering a bloodstain crucial to the reconstruction of the crime.

When bloodstains didn’t match up with items at the scene such as the purse on the bed and the bloody boots, investigators claimed the killer engaged in scene staging after the murder (Hendry, 2011). The bra clip collected weeks after the initial crime scene search was handled by several different police investigators before finally being bagged as evidence (Burleigh, 2011).

Forensic analysis by Stefanoni would have been thrown out in a United States courtroom. Her laboratory was not certified to conduct traditional DNA analysis much less Touch DNA analysis better known as Low Copy DNA Profiling (Waterbury, 2011). The knife she tested from Sollecito’s kitchen tested negative for blood, however, was determined to have been bleached. That result was later refuted when the substance on the knife was actually identified as potato starch (Rich, 2011). The knife was also determined to have been too large to have created two of the three wounds in Kercher’s neck and also too large to have left the impression in blood on the bed sheet at the crime scene (Waterbury, 2011).

It is important to emphasize here that not a trace of Amanda Knox’s DNA or fingerprints were located in Meredith’s bedroom where the crime occurred. The mixture of DNA from the bathroom could have easily been the result of trace amounts of Knox’s DNA being spread throughout the bathroom during daily use and Kercher’s blood being mixed when investigators swabbed the area. The only indication that Amanda’s boyfriend was present in the cottage was a trace amount of Sollecito’s DNA on the bra clip that could have been transferred from other areas of the cottage such as Kercher’s door to investigators gloves (Sayagh, 2010).

Another crucial error by Stefanoni was not taking a body temperature reading of the victim on November 2 when she was found. Determining time of death could only be estimated at 8 p.m. – 4 a.m. due to the forensic expert neglecting to take the victim’s temperature when she was originally found. If she had completed her job properly and taken a temperature reading before November 3rd, the data may have cleared Knox and Sollecito because they were seen at his apartment at 8:45 p.m. and Sollecito’s computer showed activity at 9:10 p.m. (Rich, 2011).

Rudy Guede’s Story
When Guede realized the mountain of evidence against him he quickly came up with an outlandish story that Kercher asked him over that night. He claimed they engaged in heavy petting but halted short of intercourse because he had to use the bathroom. While in the bathroom he decided to listen to his iPod and therefore did not hear the intruder who broke in the window, sexually assaulted Kercher, and brutally killed her. Guede stated when he came out of the bathroom he fought the stranger and he ran off. Guede then says he attempted to save Kercher and when he realized she was dead panicked and ran off (Unknown, 2009).

In the summer of 2011, 20 United States forensic experts as well as two independent Italian experts reviewed the evidence in the Knox trial. They all came to the same conclusion that the knife had not been cleaned and that the technique used to detect DNA on the knife was not reliable. Contamination was likely the source of any DNA profile of Knox found on the handle. The second piece of key evidence, the bra clip, revealed no evidence of Sollecito’s DNA according to the independent analysts (Niiler, 2011).

Many other aspects of the case were criticized such as the scene entry process, safety precautions used, and packaging and storage of evidence. Items that contained blood were found to be packaged in plastic bags which are not proper protocol. Body fluid evidence must be packaged in breathable containers such as paper bags otherwise moisture build-up results in mold growth and the degradation of DNA.

Dena Weiss PhotoAbout the Author: Professor Dena Weiss has a bachelor’s degree in chemistry and sociology from Mary Baldwin College and a master’s degree in forensic science from Virginia Commonwealth University.  She is currently working on her PhD in Business Administration with an emphasis in Criminal Justice. 

Weiss is a crime scene investigator and a fingerprint expert for a central Florida police department. Prior to working for a local police department, Ms Weiss was a serologist for the Florida Department of Law Enforcement in Tampa, Florida.

She has been actively working crime scenes and examining fingerprints for more then sixteen years. Her court experience includes testifying in court cases in over fifteen Florida counties. She has provided testimony for over 200 Federal and Circuit court cases.


Burleigh, N. (2011). The Fatal Gift of Beauty. The Trials of Amanda Knox. New York, N.Y.: Crown Publishing Group.

Hendry, R. (2011). What really happened to Meredith? Retrieved from Injustice in Perugia:

Latto, R. (2007, October 31). Halloween Italian style [Italian/American Digital Project]. .

Niiler, E. (2011, October 4). How dodgy DNA freed Amanda Knox. Retrieved from Discovery News:

Rich, N. (2011). The never-ending nightmare of Amanda Knox. Rolling Stone, 1134/1135, 86-114.

Sayagh, B. (2010). Arrested abroad: Italian precautionary detention through the eyes of Amanda Knox [Abstract].

Unknown. (2009, January 15). Summary of events and review of critical evidence in the Amanda Knox case. Retrieved from Friends of

Waterbury, M. (2011). The truth about the knife. Retrieved from Injustice in Perugia:

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.

Comments are closed.