(CNN) After more than 16 months, the US Park Police officers involved in the fatal shooting of unarmed motorist Bijan Ghaisar have been identified.

According to an amended complaint the Ghaisar family filed in US District Court on Friday, officers Alejandro Amaya and Lucas Vinyard fatally shot Ghaisar, 25, after he left the scene of a minor traffic accident in Northern Virginia on November 17, 2017.

Ghaisar, who was unarmed, was taken to a hospital, where he spent 10 days in a coma before dying on November 27, 2017.

The Ghaisar family and their supporters have spent the months since trying in vain to get answers from the US Park Police and the FBI, which is overseeing the investigation into the shooting: Who were the officers involved? Why did they pursue Ghaisar for what appeared to be a minor incident? Why wouldn't US Park Police release any information to the family?

According to their amended complaint -- which formally names Amaya and Vinyard as defendants -- the family learned the identities after it issued a subpoena to the Fairfax County Police Department, whose officers were at the scene of the shooting assisting US Park Police, a federal police force under the National Park Service and the Department of the Interior.

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