Federal agent whose gun was used in Kate Steinle killing is IDd

Flowers and a portrait remain at a memorial site for Kathryn Steinle on Pier 14 in San Francisco, Calif. on Friday, July 17, 2015. Steinle was gunned down 2 1/2 weeks ago allegedly by Juan Francisco Lopez-Sanchez, a Mexican citizen who authorities contend is in the country illegally. less Flowers and a portrait remain at a memorial site for Kathryn Steinle on Pier 14 in San Francisco, Calif. on Friday, July 17, 2015. Steinle was gunned down 2 1/2 weeks ago allegedly by Juan Francisco ... more Photo: Paul Chinn / The Chronicle 2015 Buy photo Photo: Paul Chinn / The Chronicle 2015 Image 1 of / 1 Caption Close Federal agent whose gun was used in Kate Steinle killing is IDd 1 / 1 Back to Gallery

The federal officer whose stolen service pistol fired the bullet that killed Kate Steinle in 2015, touching off a national furor over immigration policies, has been identified in court papers as an award-winning Bureau of Land Management ranger based in Southern California.

John Woychowski, 37, has been subpoenaed by the defense to testify in the case against Juan Francisco Lopez-Sanchez, the often-deported Mexican immigrant who is headed for trial on charges of murdering Steinle.

Woychowski, who lives in the small town of Imperial, was traveling through San Francisco on June 27, 2015, and had parked his car downtown when the Sig Sauer .40-caliber semiautomatic pistol was stolen from the vehicle, according to Bureau of Land Management officials. He was on duty the night it was stolen, and his car was locked, they said.

Steinle, 32, was shot to death four days later as she strolled along Pier 14 with her father. The lawyer for Lopez-Sanchez, 54, says his client found the gun under a bench, and when he picked it up it went off accidentally, hitting Steinle.

Lopez-Sanchez was on the street in San Francisco after Sheriff’s Department officials had refused a request by federal immigration officials two months earlier to hold him for possible deportation. The refusal touched off a national debate over sanctuary city policies that continues to this day.

Bureau officials refused to comment Friday on the defense subpoena, saying they can’t speak about a case in litigation. They did not say whether Woychowski had been disciplined for the theft, or if any regulatory changes resulted from the incident.

Woychowski is listed in bureau reports as based in the agency’s El Centro (Imperial County) field office, which is near the Mexican border. In 2011, he was chosen by his fellow employees there as Ranger of the Year for “exemplary protection of our public lands and unwavering dedication to visitor safety,” according to a bureau news release at the time.

The El Centro office manager at the time, Margaret Goodro, called him “a phenomenal ranger.” The release praised his “dedication to the (bureau’s) law enforcement field training program.”

Efforts to contact Woychowski were unsuccessful.

Lopez-Sanchez is due in court Friday for a hearing in which a trial date may be set for charges of second-degree murder. He is not accused of stealing the gun.

Woychowski discovered his gun had been stolen when he came back and found his car window broken, according to bureau accounts in 2015. He promptly reported the theft to his supervisor, officials said, and an incident report was filed with city police.

“I can safely say the gun was not laying on the seat in the open for folks to see as they walked by,” bureau spokeswoman Martha Maciel said in August 2015.

Sources familiar with the matter told The Chronicle at the time that the pistol was in a bag.

In papers filed June 29 in San Francisco Superior Court, defense attorney Matt Gonzalez called Woychowski’s testimony necessary for Lopez-Sanchez to be tried fairly, echoing concerns Gonzalez aired in an opinion piece published Wednesday in The Chronicle.

In that essay, Gonzalez wrote that “the Bureau of Land Management official who left his loaded weapon unsecured in a car that was burglarized has never accounted for his negligence in starting the chain of events that resulted in Steinle’s death.”

Kevin Fagan is a San Francisco Chronicle staff writer. Email: kfagan@sfchronicle.com Twitter: @KevinChron