San Francisco District Attorney George Gascón has not made a charging decision in a fatal police shooting in almost two years, leaving the officers and the families of those who were killed in limbo despite intense pressure to resolve a backlog of contentious cases.

The last time the district attorney’s office closed a fatal case was in February 2015, when it cleared the officers who shot and killed Alejandro “Alex” Nieto, a 28-year-old City College student who died in a Bernal Heights park in March 2014 after officers said he pointed a stun gun that they mistook for a pistol.

Since then, San Francisco officers have killed 11 more people, but the cases have dragged on. The city’s civil grand jury issued a report in June finding that the average district attorney’s investigation into a fatal police shooting took 20 months — a time frame the volunteer panel called “unacceptable.”

Officials with the district attorney’s office — which hasn’t pressed homicide charges against a police officer for at least the past few decades — said Gascón has been taking steps to clear the backlog and reduce the time it takes to reach a charging decision.

But representatives for the officers and members of the Police Commission said the backlog is unfair to officers, who are not only awaiting charging decisions but the outcome of internal disciplinary probes — probes that can’t be completed until the criminal investigations wrap up.

Meanwhile, community activists protest outside Gascón’s office on a weekly basis, saying the delay prolongs the pain of the families of those killed.

“These kind of a cases, it’s like taking a scab off of an old wound that goes back decades,” said the Rev. Richard Smith, rector of St. John the Evangelist Church and a member of a group pushing for punishment for two plainclothes officers who killed 21-year-old Amilcar Perez-Lopez in the Mission District in February 2015.

“People are reliving previous traumas that families have had in the past because of law enforcement, where they didn’t get justice,” Smith said. “It makes it all the more painful to sit through this all again, and the longer we wait, it’s like tearing the bandage off ever so slowly instead of all at once.”

The district attorney’s office isn’t happy with the long wait either, said Max Szabo, a spokesman for Gascón.

But since taking office in 2011, Gascón has made it a priority to provide more information to the public on the reasoning behind each charging decision, Szabo said. What once was a two-paragraph letter is now a detailed summary of events that seeks to sort through evidence and cites legal precedents.

Until recently, Szabo said, the office did not have the resources necessary to handle these complicated cases — which are held to a unique legal standard — in the thorough manner that Gascón felt the public deserved.

Prosecutors with expertise in other fields were forced to shoulder the burden on top of their existing caseloads. Another complicating factor was that Police Department homicide inspectors took the lead in each shooting case, with the district attorney’s investigators somewhat at their mercy in processing evidence and talking to witnesses.

That approach is changing. In September, Mayor Ed Lee approved funding to create a new unit in the district attorney’s office that will take the lead in investigating officer-involved shootings. Szabo said the shift will drastically speed up investigations — especially once the backlog is cleared.

“These are incredibly important investigations,” Szabo said. “It’s important that we get them done correctly, not just expediently.”

The district attorney also must make charging decisions in nonfatal police shootings as well as deaths in jail or other in-custody situations. In 2016, Gascón declined to file charges in two nonfatal shootings, one from 2013 and the other from 2014, as well as in the 2012 death of a man police were trying to arrest.

According to a Chronicle analysis, prosecutors have filed no criminal charges of any kind against officers involved in 95 shootings — 40 of them fatal — in San Francisco since 2000.

Police officials said this record shows that officers only shoot subjects when they pose an imminent threat. Critics, though, see a lack of accountability that could lead officers to resort to lethal force too carelessly.

Gascón has given no indication of whether he might file charges in the current batch of cases. He has, in the past, said the legal bar for what justifies an officer’s use of lethal force is set too low.

While Smith acknowledged that Gascón is in an unenviable position, he said, “Sometimes you have to fall on your sword.

“Nothing is going to change unless people like him step up to the plate and make these charges,” Smith said. “Archbishop Desmond Tutu used to say in South Africa, before you can have reconciliation, you have to have truth.

“We don’t have the truth,” he said, “and we need to have our day in court, where the truth has a chance of surfacing in the light of day. That’s all we’re asking. Just give us our day in court.”

Vivian Ho is a San Francisco Chronicle staff writer. Email: vho@sfchronicle.com Twitter: @VivianHo

Cases in waiting

San Francisco prosecutors must still make charging decisions in the fatal shootings of the following 11 people:

Nicholas McWherter, 26, an armed man suffering from an apparent mental crisis who shot and seriously wounded Officer Kevin Downs in the Sunset District on Oct. 14.

Jessica Williams, 29, an unarmed homeless woman who was shot in an allegedly stolen car by Sgt. Justin Erb in the Bayview neighborhood on May 19. Her death raised questions about the department’s policy allowing officers to fire at moving vehicles and prompted the resignation of then-Chief Greg Suhr.

Luis Gongora, 45, a homeless man allegedly armed with a knife who was shot by Sgt. Nate Steger and Officer Michael Mellone near a tent encampment where he lived in the Mission District on April 7. Amid a push for officers to use more de-escalation tactics, video of the shooting showed that it unfolded in 30 seconds, with officers firing beanbags at Gongora before shooting him when he allegedly charged.

Mario Woods, 26, a stabbing suspect allegedly armed with a knife who was shot by Officers Winson Seto, Antonio Santos, Charles August, Nicholas Cuevas and Scott Phillips in the Bayview on Dec. 2, 2015. Officers first fired beanbags at Woods, who refused to obey commands. Video showed he was shuffling slowly along a wall and not appearing to directly threaten officers when he was shot.

Javier Lopez Garcia, 25, an apparently suicidal man killed on Nov. 11, 2015, after he ascended to the sixth floor of a construction site near St. Luke’s Hospital in the Mission District and fired a gun. He allegedly said, “Today will be the day that I die” at the scene.

Herbert Benitez, 27, who had been behaving erratically and allegedly tried to take a police sergeant’s gun out of his holster, prompting another sergeant to shoot him in the Civic Center area on Oct. 15, 2015.

Alice Brown, 24, a woman who struggled with drug addiction. She was shot by Sgt. Thomas Maguire and Officer Michael Tursi after she allegedly sped away from a gas station at Van Ness Avenue and Pine Street, crashing into vehicles and a building and driving down a one-way street in the wrong direction.

Amilcar Perez-Lopez, 21, a Guatemalan immigrant allegedly armed with a knife who was shot by O fficers Craig Tiffe and Eric Reboli near his home in the Mission District on Feb. 26, 2015. Police said he lunged at them with the knife, but an attorney for his family said an independent autopsy showed he had been shot in the back and was possibly running in fear from the plainclothes officers, who did not properly identify themselves.

Matthew Hoffman, 32, who allegedly pulled a replica gun from his waistband, prompting two sergeants to shoot him outside Mission Station on Jan. 4, 2015. Investigators searching his phone reported finding notes about plans to force officers to kill him in a “suicide by cop” situation.

O’Shaine Evans, 26, who was shot by Officer David Goff on Oct. 7, 2014. Police said he was the driver for two passengers who had stolen a laptop out of another car near AT&T Park and had a gun in his lap when Goff approached him. Goff said Evans pointed the gun at him, forcing him to shoot, but Evans’ family has disputed the account.

Giovany Contreras Sandoval, 34, a carjacking suspect who was shot after leading officers on a three-county chase, flipping a sport utility vehicle in the Financial District and allegedly pointing a pistol at officers on Sept. 25, 2014.