A Tempe police lieutenant with nearly 20 years of experience shot and killed a robbery suspect that he believed had a gun, authorities said Friday.

Officials identified Lt. Edward Ouimette (wah-MET'), 52, as the officer who fired his weapon during a foot pursuit Wednesday, fatally hitting Dalvin Hollins, who is black.

No weapon was recovered. The officer had a body camera but it was not on at the time of the shooting, police said.

The incident began when police were called about an armed suspect demanding liquid narcotics from a pharmacy. Police say Hollins entered the store and put on a ski mask before jumping over the counter.

With his hand in a black bag, he gestured as if he had a weapon and threatened to kill three bystanders, police said in a news release.

After police released a description, an officer spotted Hollins and tried to speak with him. Police say Hollins ran through the parking lot of a senior center.

Ouimette gave chase and they were between 15 and 20 feet apart when "Hollins turned toward Lt. Ouimette and pointed what Lt. Ouimette believed to be a gun," police Lt. Michael Pooley said at a news conference.

The officer moved away and fired his weapon, Pooley said.

Hollins barricaded himself in the maintenance shed of a senior center and was found unresponsive an hour later. Emergency responders pronounced him dead.

Police Chief Sylvia Moir said a medical examiner ruled the cause of death as homicide from a gunshot wound. According to the report, the bullet went through Hollins' body from the back left area to the front right area.

Moir said "homicide" does not mean a finding of criminal conduct. However, she said the investigation was ongoing.

"Regardless of where the facts lead us, we must remain unafraid ... to safeguard Tempe," Moir said.

Hollins' family called for an outside investigation during a news conference outside City Hall.

"I want the person who killed my son to tell me sorry to my face," said Hollins' mother, Sarah Coleman.

She was joined by the Rev. Jarrett Maupin, an activist who has been leading protests against police brutality in metro Phoenix. Maupin demanded Tempe police not do the investigating.

"The Tempe police department should not be investigating itself. There are already too many red flags raised in this unfortunate incident and a clear conflict of interest," Maupin said.

Ouimette is a 19-year veteran of the department.

Hollins' stepfather, Frederick Franklin, described him as "a good kid" who fell in with the wrong crowd.

Hollins was "trying to be something that he wasn't," Franklin said.

His stepson was in the process of being diagnosed with bipolar disorder and something "must have made him snap" on Wednesday, according to Franklin.

Hollins had broken up with his girlfriend because he was unemployed, and he had trouble learning in school and processing information, said his stepfather. Franklin says Hollins fell through the cracks of the state's mental health system.

According to court records, Hollins was placed in a diversion program for pot possession in 2014.