The Baltimore police detective who was fatally shot in the line of duty last week was shot with his own gun, Police Commissioner Kevin Davis said Wednesday.

Detective Sean Suiter was shot in the line of duty on Nov. 15. He died the next day.

Davis also said there was evidence of a struggle on Suiter's clothing. Davis said this remains a homicide investigation.

Davis said that the acting U.S. attorney told him that Suiter was set to testify the day after he was killed in a grand jury investigation involving some Baltimore police officers who were indicted, but he was not targeted because of that.

In course of his career with the Baltimore police, Suiter worked cases with two members of the Gun Trace Task Force in at least 25 cases, mostly drug cases.

"I am now aware of Detective Suiter's pending federal grand jury testimony surrounding an incident that occurred several years ago with BPD police officers who are federally indicted in March of this year," Davis said. "Detective Suiter was not the target of any ongoing criminal investigation."

Suiter and his partner were looking for a witness to an unsolved 2016 homicide, police said. The partner immediately took cover at the time of the shooting and called 911, Davis said.

Three shell casings were found at the scene, and all of them match Suiter's service weapon, police said.

On Monday, all or part of a bullet was found after an autopsy, sources said, provided more accurate information about the bullet's path. It appears the new evidence was found embedded in the ground.

While at least three shots were fired, just one struck Suiter in the head at close range. 

A GoFundMe page has been set up for Suiter's family.

Anyone with information is asked to call 410-396-2100, text tips to 443-902-4824, call Metro Crime Stoppers at 866-7LOCKUP, or call the FBI at 800-CALL-FBI, Option 4.