Court overturns murder conviction of man identified by DNA cold hit

A state appeals court today overturned the murder and rape conviction of a San Francisco man who was identified as a suspect 17 years after the crime as a result of a DNA “cold hit.”

The Court of Appeal ordered a new trial for John Davis, 43, for the 1985 murder and rape of commercial photographer Barbara Martz, 28, in her home in the Potrero Hill District of San Francisco.

A three-judge panel unanimously ruled that Davis' 2007 trial in San Francisco Superior Court was unfair because of two errors: jury misconduct in independently analyzing DNA evidence and the denial of an opportunity for Davis' lawyers to question two expert witnesses.

“We find that juror misconduct and multiple violations of Davis's constitutional right to confrontation require us to reverse the judgment and remand this case for a new trial,” Justice Paul Haerle wrote.   

Martz was stabbed to death and raped on the evening of Dec. 4, 1985. Police later speculated that she might have come upon a burglar when she came home from grocery shopping that evening.

At the time, Davis was 18 and living one block away.

He was not considered a suspect until 2002, when a so-called “cold hit” matched a DNA sample from the crime to Davis' DNA in a state database.

Davis was then serving a robbery sentence at Pelican Bay State Prison.

He was charged with the murder and rape in 2003 and convicted and sentenced to life in prison without parole in 2007.

At the time he was charged, San Francisco police said the case was the first time that newly developed DNA technology enabled them to solve a violent crime in the city with no previously known suspect.

Seth Steward, a spokesman for District Attorney Kamala Harris, said late today that prosecutors had no immediate comment. Davis' appeal lawyer, Stephen Bedrick, could not be reached for comment.

The two witnesses whom Davis' lawyers were unable to question were the medical examiner who prepared Martz's autopsy report and a San Francisco police criminalist who wrote a report on Davis' DNA.

The appeals panel said Davis' constitutional right to confront witnesses against him was violated when prosecutors used other experts who had not written the reports to present the information to the jury.

“In this case, the evidence that was admitted in violation of Davis's confrontational rights was crucial to his conviction,” Haerle wrote. 

Haerle was joined in the ruling by Justices Anthony Kline and James Richman. 

The court also said jurors improperly used a formula suggested by a jury member who was a doctor to calculate that the odds were one in 8 million that the DNA came from one of Davis' brothers rather than Davis.

Can’t get enough crime stories? Check out The Examiner’s Law & Disorder Crime Blog.

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