A man who was killed in November in a shootout with an Anchorage police officer was behind five homicides — including two double murders — in the city last summer, police said Wednesday.

Homicide detectives with the Anchorage Police Department "have established sufficient probable cause" to conclude that James Dale Ritchie, 40, was responsible for those killings, according to a statement released Wednesday morning.

Officials with APD and the FBI did not provide any additional information on the investigation beyond that statement Wednesday, despite repeated requests. Each agency referred questions to the other.

"The revolver Ritchie had in his possession in November was linked to five homicides cases as the murder weapon," APD spokeswoman Renee Oistad wrote. "Homicide detectives were able to establish Ritchie possessed the .357 Colt Python before any of the killings and that he acted alone."

All investigations into Ritchie are now closed, she added.

In November, police said Ritchie fired six rounds at officer Arn Salao in a shootout that began after Salao contacted Ritchie early on the morning of Nov. 12 after a call about an unpaid cab fare in downtown Anchorage. Ritchie opened fire on the officer, police said, leading to Salao and Sgt. Marc Patzke returning fire and killing Ritchie near Fifth Avenue and Cordova Street.

The five homicides from last summer that Ritchie has been found responsible for are:

• The July 3 killings of Brianna Foisy, 20, and Jason Netter Sr., 41, on a bike path near Ship Creek;

• The July 29 death of 21-year-old Treyveonkindell Thompson on Bolin Street in East Anchorage;

• The double homicide of Kevin S. Turner, 34, and Bryant "Brie" DeHusson, 25, on the morning of Aug. 28 at Valley of the Moon Park.

Police had previously concluded that Ritchie killed Thompson, but the investigation into the two double murders had remained open.

It was unclear why authorities were not revealing any information about how they determined when Ritchie had possession of the revolver, any possible motives for the crimes or pre-existing relationships between Ritchie and the victims, and his activities in Anchorage in the period before, during and after the murders.

Staci Feger-Pellessier, a spokeswoman for the FBI in Anchorage, said in a text message Wednesday afternoon that APD was the lead investigative agency, despite APD saying earlier in the day that additional requests for information should go through the FBI.

Feger-Pellessier said the FBI "provided safe street task force members and help from our Behavioral Analysis Unit" in the investigation, but would not provide further details.

"I can't answer why they (APD) referred to us" for questions, Feger-Pellessier said via text.