DETROIT -- A man charged with setting a house fire that killed a Detroit firefighter in exchange for $20 has pleaded guilty to second-degree murder and agreed to testify against a co-defendant, authorities said Thursday.

Darian Dove's guilty plea this week was disclosed at a news conference where charges were announced against his alleged accomplice, Mario Willis, 27, of Detroit.

Firefighter Walter Harris died while trying to put out the fire in an abandoned house in November 2008. The two-story structure fell on him. His death brought new attention to the danger of responding to fires in a city with thousands of vacant ramshackle homes.

Willis took Dove, his handyman, to the house on Kirby Street and asked him to set the fire for $20, the Wayne County prosecutor's office alleges.

"$20 -- $20 million. It wasn't worth his life," Fire Chief Harry Brown said of Harris. "It cheapens it a lot more by saying $20. ... If you're doing this think about the firefighters' families."

Prosecutor Kym Worthy said Willis had "some connections" to the house, but she declined to say whether he owned it. She would not discuss a motive.

Willis' lawyer said he was surprised by the charges.

"Our hearts go out to the Harris family," Odie Uddyback said. "A fireman's life is valuable, and we believe the commitment to our community was the highest honor. But it has nothing to do with us. We don't know what the proofs are."

A message seeking comment was left with Dove's lawyer, Robert Kinney.