A decades-old murder case will remain unresolved — for now — after an appeals court late Monday agreed to hear San Francisco District Attorney George Gascón’s challenge of the release of a potentially damaging memo about the Police Department’s DNA testing lab.

Superior Court Judge Charles Haines informed attorneys in the murder case of James Mayfield on Tuesday morning about the Court of Appeal’s decision temporarily staying his order to release portions of the memo to Mayfield’s attorneys.

Mayfield, 65, is accused of raping and murdering Jenny Read, a 29-year-old sculptor, during a residential burglary in 1976. Her body was found inside her Potrero Hill home on May 19 of that year. Mayfield, a Bayview church deacon, was arrested in 2009 after a DNA hit linked him to the crime.

In the lead-up to Mayfield’s trial, Mayfield’s attorneys sought the release of a memo authored by Rockne Harmon, a former prosecutor and consultant specializing in DNA cases who advised the District Attorney’s Office last year after a scandal at the crime lab.

Harmon’s memo was reportedly critical of testing procedures at the DNA lab. Prosecutors have challenged the release, saying the memo is confidential attorney “work product.”

Gascón’s opponents in the race for district attorney have attacked his office for not being transparent about the issue.

Haines said Tuesday that the appeals court could issue a ruling as soon as a week from now, or much later. In the meantime, the trial is on hold.

aburack@sfexaminer.com