Valencia Park man in custody after he claims he fatally stabbed wife

Man entered sheriff's substation, turned self in

SAN DIEGO - A Valencia Park man is in custody after he walked into the Imperial Beach sheriff's substation Wednesday afternoon and told authorities he killed his wife.

Sheriff's officials said the man entered the substation on 845 Imperial Beach Blvd. at about 4 p.m. Wednesday and claimed that he killed his wife.

Authorities said they believe the man stabbed the woman multiple times in the parking lot of the substation. Homicide investigators found the body at the back of the substation next to a white Nissan pickup truck.

Detectives say when the man turned himself in, he had their two toddlers in his arms.

"He just said it rather matter-of-factly that he'd just killed his wife," said sheriff's Lt. Glenn Giannantonio. "He complied with the deputies' demands and orders and put the children down. He had a knife in his waistband. Without even being asked or told to, he took the knife out and dropped it on the ground."

Sources tell 10News the man accused in the stabbing is Marvin Duncan. According to court documents obtained by 10News, he and his wife divorced last September. Six other court cases were found involving domestic issues.

10News cameras captured a homicide detective and two sheriff's deputies arriving at Duncan's Valencia Park home.

Neighbor and friend Cesar Gonzales was shocked when 10News told him Duncan had turned himself in a few hours earlier.

"To be honest… it's pretty shocking, you know, because he was so like a family person," said Gonzales.

Gonzales told 10News that Duncan was former U.S. Navy and currently worked at the NASSCO shipyard, where he had been employed for the past 30 years. He described Duncan as a family man.

"He was talking about the kids most of the time because he wanted to have the kids… always wanted to have the kids," said Gonzales.

The children, who were not injured, are now with Child Protective Services until family can take responsibility for them. Detectives are not sure if they witnessed the stabbing.

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