The body of a woman who had been critically stabbed was discovered in the parking lot of the Imperial Beach Sheriff's Substation Wednesday after a man walked into the station and allegedly told deputies he had killed his wife.



According to officials, the stabbing victim was found on the ground, just outside a white truck, shortly before 4 p.m. at the IB Sheriff’s Substation parking lot located at 845 Imperial Beach Blvd.



Sheriff’s investigators say a man buzzed the station's intercom at around 3:40 p.m. and reported he had just killed his wife. Deputies say the suspect was holding two toddlers when he allegedly confessed to the fatal stabbing.

When deputies asked the man if he had a weapon, he pulled a knife out from his waistband and set it down in front of officials.

The man -- now identified by officials as Marvin Duncan, 59 – was detained by deputies on the spot.

He told officials his wife was on the west side of the station.

When deputies went out to the parking lot, they discovered the critically injured woman on the ground, suffering from stab wounds.

Officials say the woman was still breathing, but succumbed to her wounds shortly after being found by deputies. She died at the scene, officials confirmed.

As of right now, investigators believe the suspect stabbed his wife there, in the parking lot in front of the substation.

The children were not injured, Lt. Glenn Giannantonio with the San Diego County Sheriff’s Department said.



“I was just in with the children. They seem fine. We have some professional staff members that are playing with them and taking care of them. Paramedics were here and checked them out and physically they seem to be doing okay,” Lt. Giannantonio added.

Deputies say the kids are now in the custody of Child Protective Services. Their names and ages were not released.

Deputies say the family is not from Imperial Beach, but they are San Diego residents.

The victim’s death is under investigation. Officials have identified the victim as Rocio Duncan, 36. Deputies say the couple is married, but further details on the background of their relationship have not yet been released.

At this point, investigators are combing through surveillance video from the substation to see how the deadly stabbing played out.

Any witnesses with information on this case are asked to call Homicide Detail at (858) 974-2321 or (858) 565-5200, or Crime Stoppers at (888) 580-8477.



Marvin has been booked into San Diego Central Jail on one count of murder. He's scheduled to appear in court Friday.

Check back for updates.