One of Fresno's most horrific crimes, the Marcus Wesson murders, took place 15 years ago

FRESNO, Calif. (KFSN) -- The overgrown grass and weeds of a vacant lot now sit where the worst mass murder in the city's history took place.

"Certainly leave an undeletable image across this city and hopefully never ever be replicated in any form," said Fresno Mayor Lee Brand.

15 years ago, nine of Marcus Wesson's children and grandchildren were shot dead and stacked in a back bedroom of their Central Fresno home.

"All the bodies were stacked up like cordwood," said Police Chief Jerry Dyer.

The residence that once stood at 761 West Hammond Avenue may be gone, but the memories still haunt many of the first responders who discovered the grisly details that day.

Chief Jerry Dyer had been Fresno's Chief of Police for less than three years when he got the call.

"It was something that I don't think anyone in law enforcement will ever forget," Dyer said.

Wesson sits on death row at San Quentin.

In the summer of 2005, he was convicted of killing nine of his children.

He had fathered them with his wife, daughters, and nieces.

"This was an incestuous relationship we'd had never seen. Then we found out about their belief systems, and it appeared on every indication that they were operating as a cult," Dyer said.

Wesson believed he was Jesus and if anyone tried to separate the family, then they would all go to heaven.

He even went so far as to purchasing caskets from a local antique store months before the mass murder took place.

"He had such incredible influence over his children and wives that this was the outcome," Dyer said. "That he was able to control the mind of people to do the unthinkable very similar to what Charles Manson did."

Marcus Wesson is 72 now and is unlikely ever to face execution.

"Marcus Wesson was a menace to society, and I will never forget," Dyer said.

Only 13 people have been executed in the 33 years since California's death penalty was reinstated, none since 2006.