San Quentin State Prison Death Row inmate Kenneth Friedman was pronounced dead in his single cell Sunday morning, prison spokesman Lt. Sam Robinson said.
Friedman's death is being investigated as a suicide, Robinson said. His body was found at 5:24 a.m.
A Los Angeles County jury sentenced Friedman, 58, to death on Dec. 2, 2005, Robinson said.
Friedman was convicted of the strangulation murder of one-time drug dealer Peter Kovach, 26, and an innocent bystander, Ted Gould, 29, on Oct. 26, 1994, Robinson said.
The men were abducted from a Torrance telecommunications store where they worked, Robinson said.
Friedman was on Death Row since Dec. 14, 2005.
Since 1978 when California reinstated the death penalty, 57 condemned inmates have died of natural causes, 21 committed suicide, 13 were executed in California and one in Missouri, Robinson said. Six other inmates died of other causes.
There are 728 inmates on California's Death Row, Robinson said.