A man who was convicted of killing three people, then fought for two years to end his appeals and be put to death, was executed early Friday.

David Dawson, 48, died by injection at 12:06 a.m. at Montana State Prison, becoming the first person executed in the state since 1998.

Witnesses said he declined to make a final statement. Earlier, when Dawson was in a holding cell, "My understanding was he had ear plugs in and was listening to music and really was pretty focused and quiet," warden Mike Mahoney said.

Earlier this summer, Dawson won the right to fire his attorneys, end his appeals and move forward with his execution. The attorneys had argued that, among other things, Dawson's decision to end his appeals was influenced by his time on death row and the suicides of other inmates.

In a hearing last December, Dawson told a judge the suicides didn't affect him and argued repeatedly that the lawyers were not representing his interests. State and federal courts ruled that Dawson was mentally sound and made his requests to end his appeals knowing the consequences.

On Thursday, the Montana Supreme Court denied a request by civil liberties groups to delay the execution, ending a flurry of last-minute appeals.

Dawson was sentenced to death in 1987 after taking a family captive for days in a motel room in Billings a year earlier. David and Monica Rodstein and their 11-year-old son, Andrew, were killed, while their daughter, Amy, was rescued by police. She testified against Dawson at trial.

Civil liberties groups this summer launched an effort to halt the execution.

The groups, led by the American Civil Liberties Union, argued lethal injection is cruel and unusual punishment, and should be deemed unconstitutional. They asked that Dawson's execution, and any others in the state, be postponed until the matter can be addressed.

Dawson opposed the groups' efforts, and state and federal courts refused to intervene. That cleared the way for his execution.