Seal Beach Police release details of 2016 arson killing

Seal Beach police asked for the public's help Monday to learn further details of a cold-case arson killing six years ago.

Police on Monday identified the suspect as 61-year-old William Pratt. Investigators suspect Pratt killed 67-year-old John Donnelly in an arson fire at his apartment about midnight April 30, 2016, at 211 17th St., according to Seal Beach police Lt. Nick Nicholas. Police found an accelerant used to ignite the fire on the apartment's stairwell, Nicholas said. 

Pratt is dead. He sustained fatal injuries in a fight with another inmate at Deuel Vocational Institution on June 8, 2020 and died less than a month later, on Aug. 7, 2020, from the injuries sustained in the fight, according to the state Department of Corrections.

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Pratt was sentenced to nine years in prison in May 2017 for assault with a deadly weapon, which was his second strike conviction, according to the Department of Corrections.

Pratt was a "very well known person, especially among the homeless in the Seal Beach area, and a lot of those homeless individuals were fearful of Pratt," Nicholas said.

Knowing that Pratt is dead, police hope more transients in the community will step forward and help provide more details to investigators, Nicholas said.

Anyone who has information relevant to investigators was asked to call 562-799-4100.