Richard Leroy Carlson, 31, was sentenced to 15 years to life for the second-degree murder of Eleanor Carlson, plus one year for use of a knife in the killing, Deputy District Attorney Tom Brown said.
Carlson was acquitted of first-degree murder when he was convicted of the lesser charge in October.
San Rafael police found 72-year-old Eleanor Carlson's body in her home at 215 C St. in San Rafael when they responded to an alarm call around 4 a.m. on March 15, 2010.
Carlson, who was adopted by Eleanor Carlson and her late husband, was arrested without incident by San Rafael and Hayward police on Grand Avenue near the Hayward BART station on March 16.
San Rafael police also said Carlson's mother obtained a temporary restraining order against him after a violent confrontation with him in January 2010.
Deputy Public Defender Pedro Oliveros argued during trial that the slaying was manslaughter because Carlson was abused by his mother when he was a child, Brown said.
Brown argued that the slaying, in which Carlson used a Leatherman utility tool, was not a "heat of passion" manslaughter but first-degree murder.