Inmate convicted in Phoenix's 'serial shooter' attacks dies in prison; cause of death unknown

An Arizona death row inmate convicted of killing six people in Phoenix's "serial shooter" attacks has died in prison.

Prison officials say 40-year-old Dale Hausner was found unresponsive in his cell in Florence around noon Wednesday. He was pronounced dead at a hospital about an hour later.

Authorities say the cause of death is under investigation.

Hausner was sentenced to die for his convictions in a series of random shootings in the Phoenix area in 2005 and 2006.

Investigators say Hausner preyed on pedestrians, bicyclists, dogs and horses during a 14-month conspiracy that occasionally included his brother and his former roommate, Sam Dieteman.

Dieteman pleaded guilty to two of the killings.