Alleged Serial Killer Who Targeted San Diego’s Homeless Found Mentally Incompetent to Stand Trial

A San Diego serial killer arrested for the murder of three homeless men in July was found mentally incompetent to stand trial recently by Superior Court Judge Steven Stone.

Stone ruled that Jon David Guerrero, 39, will spend the next three years at Patton State Hospital—a forensic psychiatric hospital in San Bernardino County—according to San Diego County District Attorney Spokesman Steve Walker.

Public Defender Dan Tandon, who represented Guerrero, said that his client was living in an apartment in downtown San Diego at the time but has been homeless throughout his life. He commented briefly on the case.

“Dr. Matthew Carroll did the examination, and he determined that Mr. Guerrero is not competent to stand trial,” Tandon said. “All court proceedings are suspended until he’s competent or after the three years he will spend at the hospital seeking treatment and medication.”

Tandon said Carroll determined his client suffered from mental illness based on his review of Guerrero’s records.

Guerrero was arrested for attacks on two homeless men and three homicides on July 15 shortly after surveillance video footage and a sketch of him was released by police.

According to a criminal complaint, Guerrero was wanted for the murder of three homeless men and the attempted murder of another the day he was caught by police. He was charged with three homicides with a deadly weapon, two counts of arson to property and two attempted murders.

San Diego police say that Guerrero attacked the upper torsos of his victims and set fire to some.

His homicide victims include 53-year-old Angelo DeNardo, Shawn Longley and 23-year-old Dionicio Derek, who later died in the hospital. Those who survived Guerrero’s attacks were 55-year-old Joseph Papadelis and Manuel Mason.

Guerrero may appear before a judge in three years or earlier if he returns to competency before then, Tandon said.

Jordan Frias

Jordan Frias is an editorial assistant at Boston Herald and a contributor of Spare Change News. He is vice president of the New England Chapter of the Society of Professional Journalists and a graduate of Northeastern University's School of Journalism.

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