Two 16-year-old boys have been charged with first-degree murder in the Englewood slaying earlier this month of the chef at a popular Denver restaurant, officials announced Monday.

Englewood police say the pair are also accused of attempted aggravated robbery in the Oct. 1 death of Nicholas “Nick” Andrew Lewis on the 3000 block of South Acoma Street.

Authorities say the pair were charged on Oct. 21 after an “exhaustive investigation.” Both were in custody on unrelated accusations when they were formally accused in Lewis’ killing.

Sgt. Brian Cousineau, an Englewood police spokesman, said he could not comment on whether the teens were being charged as adults. He also declined to say what investigators believe motivated the killing.

“We do have a theory, but I can’t release that,” Cousineau said.

Lewis, 33, was a chef at Blackbird Public House and a father to a young boy. He was an Englewood resident.

Brian Midtbo, Blackbird’s owner, previously told The Denver Post that Lewis was a devoted father of an 8-year-old.

“He’s one of the nicest people I’ve ever met in my life,” Midtbo said. “He worked all night and got up every morning and took his kid to school. Nick was a great guy and a great dad. Nick actually never had anybody that didn’t love him.”

According to his obituary, Lewis was described as a devoted father who loved spending time with his son, Liam, teaching him about Colorado’s outdoor life.

“Nick was a successful chef in many of Denver’s finest restaurants,” the obituary said. “Just this past summer he was excited to be hired as the Executive Chef at the Blackbird Restaurant and was recently promoted to Culinary Director overseeing its three affiliate restaurants. He recently had the honor to cook for the Governor of Colorado at the Governor’s Mansion in Denver.”

The teens’ names were not released.

“Every single detective was assigned this case,” Cousineau said. “All of our investigators dropped everything they were doing and were focused on this case.”

He added: “We don’t have a lot of these, and so when we do end up getting a homicide in our city, our citizens expect it to be solved. We expect to solve it as well. We pour as much resources into it as possible.”

More than a dozen officers were assigned full-time to investigate Lewis’ killing.

Englewood police say they will release more details on the case Wednesday during a news conference. Prosecutors on Monday declined to comment on the case until then.

“The 18th Judicial District Attorney’s Office will make no comments on these cases until the news conference,” Vikki Migoya, spokeswoman for the 18th Judicial District Attorney’s Office, said in a news release. District Attorney George Brauchler is expected to speak during that media briefing.

Englewood police say they found Lewis on Oct. 1 while responding about 8:30 p.m. to a report of shots fired on the 3000 block of South Acoma Street. Investigators said he was “on the ground with several gunshot wounds.”