A DNA expert took the stand Thursday at the second-degree murder trial of Adam Mann in the Supreme Court in New Westminster. Mann is accused of stabbing and killing Tori Dunn during an alleged home invasion in June of 2024 at the house she shared with her boyfriend in the Port Kells neighbourhood of Surrey. Janny Lau, a forensic biologist who works in the RCMP National Forensics Lab at the force’s E-Division headquarters, testified about testing exhibits related to the case against known samples of Dunn and Mann’s DNA. “We always state that there are two possibilities and I’m just telling you which one is more likely once we do the calculation and determine how rare the profile is,” Lau told the jury. She said DNA testing on blood found on the blade of a large kitchen knife located in the neighbourhood near the crime scene showed it was a very probable match to Dunn. Lau told the court the likelihood the blood came from someone other than Dunn was one in 290 quintillion. A quintillion is one followed by 18 zeros. Testing confirmed the presence of DNA on the knife handle as well. Lau told the court that DNA was of mixed origin from three different people. When tested against the known DNA sample taken from Mann by an investigator, she said her results showed it was 2.8 quadrillion times more likely one of the DNA profiles on the knife handle originated from Mann than from a random member of the population. A quadrillion is 1 followed by 15 zeros. Testifying about DNA testing on a grey sweatshirt found outdoors near Dunn’s house, Lau told the court two DNA profiles found on the sleeve were likely matches to both Mann and Dunn. Trafford Wace, Dunn’s boyfriend, previously testified that the suspect who stabbed Dunn in the couple’s living room was wearing a grey sweatshirt. After the lunch break, Lau testified about DNA analysis on a swab taken from Dunn’s iPhone, which Wace said was missing after the attack. The phone was subsequently located by police in a grassy area in the neighbourhood. Lau told the court the results showed it was between 12 and 17 billion times more likely the DNA sample on the phone matched the known sample from Mann, rather than a random unknown member of the population. In cross-examination, defence lawyer Paul McMurray asked Lau several questions about the databases the RCMP uses for DNA analysis. She testified that at the time of her initial examination on the DNA results in this case in June of 2024, the force relied on the RCMP Canadian Caucasian population database. Lau said the RCMP has since switched to a stratified population database that includes a number of different ethnicities. Prior to testifying in this case, she re-analyzed the data used in this case with the stratified database and noted similar results to the original analysis using only the Caucasian database. The Crown has told the judge it intends to call one more witness and expects to wrap its case by midday on Friday. Defence has said it needs time to get instructions from Mann and suggested it would not likely be ready to proceed on Friday afternoon.
