(CNN) -- Baltimore police officials have asked the FBI to take over the investigation into the fatal shooting of a homicide detective the day before he was set to testify in a police corruption case involving fellow officers.
Sean Suiter, 43, was shot in the head with his own gun after struggling with his killer November 15 in west Baltimore. Suiter died the next day at a hospital. The 18-year department veteran had been investigating a killing when he noticed a man acting suspiciously before the shooting.
Baltimore Police Commissioner Kevin Davis said the FBI and federal prosecutors have said Suiter was not a target of the investigation into several Baltimore officers with a gun task force who were federally indicted in March. There is no apparent connection between Suiter's killing and the corruption case, the commissioner said.
In the December 1 letter to FBI Director Christopher Wray, Davis said, "the circumstances surrounding Detective Suiter's killing are significantly complicated" by the fact he was set to give grand jury testimony the day after he was killed.
"I am growing increasingly uncomfortable that my homicide detectives do not know all of facts known to the FBI or (United States Attorney's Office) that could, if revealed to us assist in furthering this murder investigation," Davis wrote.
"I respectfully request the FBI to investigate murder of Detective Suiter," the police commissioner wrote.
In an interview with CNN, Baltimore police spokesman T.J. Smith said Davis decided to reach out to the FBI because "he thought it was in the best interest of this agency and this investigation."
"Our men and women of the Baltimore police department homicide section are more than capable of investigating this case," Smith said.
The FBI officials couldn't be reached for comment Monday.
The FBI has been involved in the investigation from the start, along with the Bureau of Alcohol, Tobacco, Firearms and Explosives and the Drug Enforcement Agency, according to Davis.
Law enforcement agencies are offering a $215,000 reward for information leading to the arrest and conviction of Suiter's killer.
The funeral for Suiter, a father of five, was held last Wednesday.
CNN's Chris Boyette and Dave Alsup contributed to this report.
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