DNA expert says blood on knife is a highly probable match to Tori Dunn in Adam Mann trial

A DNA expert testified Thursday at Adam Mann’s second-degree murder trial in the Supreme Court in New Westminster. Mann is accused of stabbing and killing Tori Dunn during an alleged home invasion in June 2024 at the Port Kells home in Surrey that she shared with her boyfriend. The Crown told the judge it plans to call one more witness and expects to finish its case by midday Friday. The defence said it needs time to get instructions from Mann and suggested it may not be ready to proceed Friday afternoon.

Janny Lau, a forensic biologist at the RCMP National Forensics Lab at the force’s E-Division headquarters, described comparing evidence from the case with known DNA samples from Dunn and Mann. She told the jury that DNA analysis presents two possibilities; calculations indicate which is more likely and how rare the profile is.

Lau said DNA testing of blood on the blade of a large kitchen knife found near the crime scene showed a very probable match to Dunn. She testified that the odds the blood came from someone other than Dunn were one in 290 quintillion, or one followed by 18 zeros. DNA was also found on the knife handle and was a mixture from three people. Compared with a known sample taken from Mann by an investigator, the results showed it was 2.8 quadrillion times more likely that one of the profiles on the handle came from Mann than from a random member of the population. A quadrillion is one followed by 15 zeros.

Lau also testified about a grey sweatshirt found outdoors near Dunn’s home. Two DNA profiles on a sleeve were likely matches to Mann and Dunn. Dunn’s boyfriend, Trafford Wace, previously testified that the suspect who stabbed Dunn in the couple’s living room was wearing a grey sweatshirt.

After the lunch break, Lau discussed DNA analysis of a swab taken from Dunn’s iPhone. Wace said the phone was missing after the attack; police later found it in a grassy area in the neighbourhood. Lau said it was between 12 billion and 17 billion times more likely that the DNA sample on the phone matched Mann’s known sample than that of a random unknown person.

During cross-examination, defence lawyer Paul McMurray asked Lau about the databases the RCMP uses for DNA analysis. Lau testified that when she first examined the results in this case in June 2024, the force used the RCMP Canadian Caucasian population database. She said the RCMP has since moved to a stratified population database that includes several ethnicities. Before testifying, she re-analysed the case data using that database and found results similar to the original analysis, which used only the Caucasian database.