NBC 7’s Steven Luke explains how investigators used genetic genealogy technology to solve the crime.
Using cutting-edge, DNA matching technology that has been resurrecting cold cases across the country, police in La Mesa have made an arrest in a case involving a victim who was stabbed to death with a sword in his home nearly 13 years ago.
As Scott Martinez, 47, entered his home on June 17, 2006, he was stabbed several times by a suspect armed with a sword. Martinez did not survive the vicious attack.
By the time police arrived at the scene of the crime, the suspect was gone. Two blood stains had been left behind belonging to a man who was not Martinez. Investigators believed the blood stains were from the suspect who likely cut himself while committing the killing.
Over the years, the case grew cold – that is, until Thursday.
Nearly 13 years after the slaying, the La Mesa Police Department announced genetic genealogy technology had helped detectives finally arrest a suspect in the case.
At a Thursday news briefing, LMPD Chief Walt Vasquez confirmed the suspect is Zachary Bunney, who was 26 years old and living in La Mesa at the time of the crime. Bunney, now 39, is a resident of Hillsborough, Oregon; he was arrested there on Jan. 10 in connection with the killing of Martinez.
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The victim’s daughter, Angie Martinez, spoke to reporters Thursday and said her family never thought this day would come. She said she’s grateful for the tireless work of detectives.
“Without all of their hard work we would not be receiving the gift that we have gotten, which is peace of mind and final closure,” Angie said. “Words cannot express what this news has done for all of us who knew and loved my father. It’s a day that we thought we would never see.”
Vasquez said that over the years investigators conducted DNA testing of multiple persons of interest in the case, but none were a match.
Connie Milton, a supervising criminalist for the San Diego County Sheriff’s Department crime lab, has been working on this case since the beginning.
Milton said the blood stains left at Martinez's home were tested time and time again. In all, she said at least 20 suspect references have been submitted – and excluded – throughout this cold case.
In 2016, Milton said the LMPD and SDSO used new forensic technology to try to identify a suspect. Vasquez said LMPD Det. Ryan Gremillion took over the case at that time and thoroughly reviewed the evidence once more.
In April 2018, DNA matching technology was used to arrest Joseph DeAngelo, the accused infamous “Golden State Killer” linked to dozens of horrifying crimes and killings across California between 1976 and 1986.
Milton said that case and DeAngelo's arrest "pioneered the use of genetic genealogy to search DNA profiles."
In September 2018, Gremillion consulted with Virginia-based DNA tech company Parabon NanoLabs, which offers genetic genealogy services and something called DNA “phenotyping” – the process of using unidentified DNA evidence left behind at a crime scene to predict someone’s ancestry.
That process matches DNA against a database called GEDMatch, which includes about 1.2 million DNA samples.
The following month, once the DNA analysis was completed, Milton said Gremillion had zoned in on a name for a potential suspect in the cold case: Bunney.
The DNA of one of Bunney's extended relatives, likely a second or third cousin, was in the GEDMatch database and was traced back to Bunney.
The detective got work locating the suspect.
Earlier this month, all of the pieces finally came together.
As 2019 began, Gremillion told Milton that investigators were traveling to Oregon to find Bunney and obtain a DNA sample to test against the original samples from the Martinez crime scene.
On Jan. 9, detectives found Bunney and obtained an oral DNA swab from him. The sample was overnighted to the SDSO crime lab in San Diego and was examined on Jan. 10.
By 1:30 p.m. that day, criminalists had matched the sample to the original evidence and linked Bunney to the killing. He was arrested that day in Oregon. On Thursday, he was extradited to San Diego.
Bunney is set to appear in court Friday. He will face one count of murder, which carries a maximum sentence of 26 years to life in prison.
At this point, the motive for the murder remains unknown.
In November 2018, this type of DNA technology helped the Carlsbad Police Department in San Diego's North County with a similar break in the 2008 cold case of Jodine Serrin, 39.
In that case, detectives tracked down David Mabrito as the suspect. Mabrito had died from suicide in 2011, but advancement in DNA matching technology coupled with genealogical experts linked him to Serrin’s killing.
