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A Philadelphia cop was arrested Wednesday after speeding alongside another officer led to the death of a 50-year-old pedestrian crossing the street earlier this year.

Adam Soto, 24, has been charged with involuntary manslaughter and homicide by vehicle for the Jan. 31 incident in which he hit and killed Philadelphia resident Daniel Dimitri.

Authorities said Soto was "recklessly driving" at the time. He was driving over 80 miles per hour in a school zone with a 30 mph speed limit, the district attorney's office said.

Officer Adam Soto Philadelphia Police Dept.

Another off-duty officer, 25-year-old Tony Forest, was driving at high speeds in the same direction as Soto at the time of the accident, police said. Forest has not been arrested, but was charged with violating the department's policies.

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“This is a particularly egregious act,” First Assistant District Attorney Kathleen Martin said in a statement. “Officer Soto, who once took an oath to serve and protect, is charged with literally running down and killing one of his fellow citizens.”

Both men, who served the department for three years, surrendered themselves to police Wednesday and were suspended for "30 days with the intent to dismiss," officials said.

But after three months, Dimitri's family is still grieving and hoping for justice. Brittany Prosinski, Dimitri’s niece, said she was largely “kept in the dark” during the investigation.

“We were just told bits and pieces,” the 31-year-old said. “For the past three months, we’ve been hanging on the edge of our seats trying to get information on what happened.”

Prosinski said witnesses believe the officers were racing right before her uncle was hit. She said she wants a fair investigation and for the second cop, Forest, to be charged as well.

An undated photo of Stephanie Prosinski, from left, Daniel Dimitri and Brittany Prosinski. Courtesy Brittany Prosinski

“It took them three months to bring on charges and to arrest [Soto]. I do feel that it is because he is a cop,” she said. “If that was anyone else, it would’ve been different.”

Her uncle, Prosinki said, was a staunch supporter of the Philadelphia Police Department. She described him as an optimist who “always looked on the bright side of life.”

Soto's defense attorney Fortunato Perri called the situation tragic for everyone, including relatives of Dimitri— a local chef and carpenter born in Philadelphia. Dimtri was heading to the seafood restaurant where he worked, Chuck's Alibi, when he was struck, his niece said.

"It's a sad and tragic set of circumstances for everyone involved," Perri told NBC News.

During a news conference Wednesday, Captain Sekou Kinebrew said the investigation did not determine whether the officers were drag racing, but did point to signs of reckless driving, NBC10 reported.

The ex-cop's preliminary court hearing will be held on May 10, his lawyer said. The investigation remains open under the district attorney’s office.