The family of an Albuquerque man fatally shot outside his home as deputy U.S. marshals sought to arrest another man sent a letter to federal officials Tuesday, saying they are seeking answers in the case and intend to take legal action, their attorney said.

In the letter, attorney Robert Gorence said witness accounts described seeing Edgar Camacho-Alvarado, 23, "flailing his arms and, unable to respond to law enforcement commands" after being shot. The letter also states Camacho-Alvarado allegedly was shot in the back and shot at close range.

"If that is true, we will expect a thorough criminal investigation of the deputy marshal or deputy marshals who engaged in such egregious conduct," Gorence said.

Citing an ongoing investigation, state and federal officials have declined to comment on the family's account of the shooting and have disclosed few details in the case, except to say that Camacho-Alvarado was shot as deputy U.S. marshals were attempting to find George Bond, who was wanted in a 2014 homicide.

A New Mexico State Police investigation into the shooting is underway. Bond, 25, was arrested in the trailer park where Camacho-Alvarado died hours after the shooting, according to authorities.

Camacho-Alvarado's mother, Hermelinda Alvarado, attended a news conference Tuesday where Gorence, a former federal prosecutor, announced the family's intent to take legal action, starting with a tort claim the attorney said in the letter reportedly sent to the U.S. Attorney's office in Albuquerque that he intended to file by the end of the week.

A phone call requesting comment from the U.S. Attorney's office after business hours Tuesday evening was not immediately returned.

Gorence and his team also are conducting their own investigation into the shooting because authorities so far have not addressed key questions, including why the man was shot when authorities say they were attempting to execute an arrest warrant for someone else.

"The family doesn't know how they got to the wrong house," Gorence said. "The request of the family is to get answers because they have none."

In an interview with The Associated Press, Juan Alvarado said his grandson Camacho-Alvarado was working on his pickup truck in the driveway when federal authorities arrived and opened fire, striking down the 23-year-old in his family's driveway.

Officers fired two more shots as Camacho-Alvarado reached the trailer's front stoop while trying to escape the gunfire, Alvarado said, pointing to nicks in a metal screen door he said were put there by bullets from the shooting. After hearing shots, Camacho-Alvarado's mother emerged from the house and shouted "don't shoot," Alvarado said.

The results of an autopsy from state medical investigators would offer an account of where Camacho-Alvarado was shot, but they could take months to be released, Gorence said.

He has requested a separate autopsy be conducted by an independent pathologist that could begin as soon as Wednesday and yield quicker answers, he said.

"All I know is it's been completely non-transparent and that has raised enormous suspicions," Gorence said.