FLAGSTAFF, Ariz. — Less than a week after an Arizona man reported his wife missing, launching an expansive search that quickly turned into a criminal investigation, he admitted to killing her and pleaded guilty to murder, authorities announced Friday.

As part of a deal with prosecutors in Coconino County, Daniel Paduchowski pleaded guilty Friday to second-degree murder in the death of his 45-year-old wife, Kelly. He also pleaded guilty to tampering with physical evidence, concealment of a dead body and possession of dangerous drugs, according to a copy of the plea agreement.

The agreement, reached earlier Friday before the Flagstaff Police Department held an afternoon news conference, marks a stunning and swift resolution to a homicide case that was opened just days earlier and that could have otherwise stretched for years as it made its way through the legal system.

At the news conference, Flagstaff Police Chief Sean Connolly emphasized that it had been just six days since authorities were alerted to Kelly Paduchowski’s disappearance.

“I was at the barber. I’ve been at the dry cleaners. I’ve been to restaurants and businesses, and this has been on everybody’s mind,” he said. “When communities are not indifferent, and they are engaged at this level, these are the outcomes that you have.”

Authorities didn’t provide any details about what might have led to the killing, nor did the plea agreement include information indicating a possible motive.

Paduchowski’s attorney did not immediately respond to email and phone messages seeking comment.

Michael Tunink, a senior attorney at the Coconino County attorney’s office, said Daniel Paduchowski, 58, is expected to be sentenced to 16 years without the possibility of parole for the murder charge. His sentencing is scheduled for Sept. 10.

Authorities said Paduchowski called Flagstaff police on Sunday night, saying his wife never returned after leaving to go for a run and a swim at Lake Mary, southeast of Flagstaff.

Police said they quickly began to suspect Daniel Paduchowski had been involved in his wife’s disappearance, after the woman’s relatives found her car on the other side of town.

By Monday morning, police said, the missing persons case had turned into a homicide investigation. The Flagstaff Police Department announced Daniel Paduchowski’s arrest the next day.

As part of his deal with prosecutors, Daniel Paduchowski provided authorities with information about his wife’s remains and other evidence, including her cellphone, car keys and a weapon allegedly used to kill her, Tunink said.

Flagstaff police said they found Kelly Paduchowski’s remains on Friday morning but did not release the location, citing active “recovery efforts.”

Authorities said the search for Kelly Paduchowski was expansive, including local and federal agencies, nearly 50 search and rescue members who searched by foot, helicopter and on mountain bikes, as well as search dogs and drones. About 60 people from the community also volunteered for the search effort, police said.

Connolly, the Flagstaff police chief, said Friday that authorities have been in constant contact with the victim’s relatives, including her children.

“Since the moment I sat in the living room with Kelly’s family, I cannot tell you how impressed I have been with their strength and their resolve in handling this incredibly tragic situation,” he said.