Prosecutors say a 38-year-old Oakland man killed his girlfriend's young son, dumped his body in the water, then killed her to stop her from telling anyone.
Charles Martin III was charged Tuesday with two counts of murder with special circumstances, making him eligible for the death penalty if convicted.
Police found the body of 17-month-old Jashon Williams floating near the Berkeley Marina on Sunday _ two days after the body of his mother, Zoelina Williams, was found in nearby Aquatic Park.
Martin has not yet entered a plea.
Martin previously was convicted of killing a girlfriend's child. He pleaded guilty in 1994 to voluntary manslaughter in a plea deal that got him 11 years in prison. He was released in six years after getting credit for time served.