Richard Ferretti's family tried to be patient after he was shot and killed by an undercover Philadelphia police officer last May.

They had simple questions, really: How did an early morning search for a parking spot near St. Joseph's University end up costing the unarmed 52-year-old his life? And would the officer who shot him be held responsible for violating a policy that prohibits cops from shooting into moving vehicles?

But more than a year has passed since Ferretti died, and his relatives are still no closer to the answers they hoped to have found by now. Frustrated by the wall of silence that has met their search for closure, Ferretti's sister, Lisa Newman, and her husband, Donald Newman, filed a lawsuit on Tuesday against the city in the U.S District Court for the Eastern District of Pennsylvania.

The Newmans had, to this point, been largely reluctant to publicly criticize the investigation by the District Attorney's Office into Ferretti's death. "They were patient because they trusted the system, because they're people who believe in the system," said Kenneth Rothweiler, one of the family's attorneys. "Then they realized the system had let them down. When you don't get answers, you lose faith."

Lisa Newman and her mother, Mary Lou Ferretti, attended a news conference in a small, ornate room inside Rothweiler's Center City Office on Tuesday morning. As the lawyer recited the facts of the case, Ferretti occasionally dabbed at her eyes with a tissue, while her daughter punctuated a description of her brother's final moments with a deep sigh.

Rothweiler and the family's other attorney, Todd Schoenhaus, told the Inquirer and Daily News last month that they'd learned a local grand jury had been tasked with determining if Officer Shannon Coolbaugh should face charges for shooting Richard Ferretti on May 4, 2016.

DA spokesman Cameron Kline declined to comment Tuesday, noting the office can't discuss active investigations. It's unclear if the case's resolution is being held up by dysfunction at the top of the agency. District Attorney Seth Williams agreed to have his law license suspended while he waits to go to trial on federal corruption charges; much of the office's day-to-day operations are being managed by First Assistant District Attorney Kathleen Martin.

"The ball's been dropped by somebody," Rothweiler said. "Maybe Kathy Martin is afraid to say they're not going to indict the officer, or maybe she's afraid to say they will."

Martin released a statement Tuesday night that read: "The District Attorney's Office will seek justice on a timeline that is dictated by the facts and circumstances of each investigation. We will not be moved or swayed by the misplaced public comments of a lawyer with a vested financial interest."

In November, the DA's Office released data that showed it resolved investigations into police shootings in fewer than 60 days. The Ferretti case has dragged for 398 days, Rothweiler said during the news conference. "It's a travesty, what this family has gone through with regard to the killing of their loved one, but an additional travesty is the way they've been treated by both the police department and the Philadelphia DA's Office."

Police Commissioner Richard Ross has said it's unclear when the grand jury would announce its findings. He's also expressed concerns about the tactics that were employed by Coolbaugh, who has been on desk duty since the shooting. John McNesby, the president of the Fraternal Order of Police Lodge No. 5, did not respond to a request for comment about Coolbaugh.

A resident called 911 just before 1 a.m., and reported that Ferretti's slow loops in a Dodge Caravan around 63rd Street and Overbrook Avenue looked suspicious. He lived in the neighborhood with his girlfriend, Stacy Betts.

According to the lawsuit, Ferretti had just driven the Dodge—which belonged to Betts— to a nearby Sunoco station, where he poured $4.64 worth of gasoline into a can to later fill up his own car, which had run out of gas.

Coolbaugh and another undercover cop called for a marked patrol car to assist them when they spotted Ferretti driving the minivan. The patrol car pulled behind Ferretti with its lights flashing; according to police, Ferretti kept driving.

The undercover cops tried to block Ferretti's path with their car. They jumped out of their vehicle and told Ferretti to turn off his engine. He didn't, and Coolbaugh opened fire—even though, according to reports, a neighbor heard Ferretti yell, "I'm stopping!"

"[Ferretti] had no weapon on his person or in the vehicle," Schoenhaus said.

Rothweiler said Ferretti's three bullet wounds were all on the left side of his body, which suggests he might have already been driving past Coolbaugh when he was shot. "We'll hire a forensic expert to reconstruct the whole thing," he said.