Members of the San Francisco Police marine unit search for the bodies of two children Thursday.

San Francisco ? The mother accused of drowning her three young boys in the San Francisco Bay told relatives the day of the killings that she would “feed them to the sharks,” but family members did not take the threat seriously, a sister said Thursday.

Less than a day after 23-year-old Lashuan Harris allegedly stripped her children naked, hoisted them over a pier safety rail and tossed them into the bay’s chilly waters, relatives described Harris as a devoted and loving mother whose life began spiraling out of control when she was diagnosed with a mental illness two years ago.

Now, with Harris in custody and facing murder charges, authorities mounted an intensive, around-the-clock effort to recover the children’s bodies.

An undated family photo shows Lashaun Harris, the woman who tossed her three young children off a pier, second from right, along with sons Taronta Greely, 2, being held third from left, and Treyshaun Greely, 6, at right. Others are not identified.

While a Coast Guard helicopter spotted the body of Taronta Greely, 2, on a sandy beach more than a mile away from where his mother was arrested Wednesday night, Treyshaun Harris, 6 and Joshoa Greely, 16 months, remained missing in the bay’s churning waters Thursday.

Harris, a schizophrenic who had been living in a homeless shelter in recent months, came from a large close-knit family.

Harris’ sister Britney Fitzpatrick, 16, said Harris would often talk to herself and claimed to hear voices. “What are you laughing about?” family members would ask her when she began laughing out of context, Fitzpatrick said.

Then on Wednesday morning, she said, Harris made a comment no one believed.

“She told my momma once she was going to feed them to the sharks,” Fitzpatrick said.

“No one took her seriously,” she said.