It was sold to private investors. The sale price was not disclosed, but the home was listed for $14.5 million.
Shacknai's girlfriend, 32-year-old Rebecca Zahau, was discovered hanged in the home, according to sheriff's investigators.
Authorities said Zahau killed herself. Her family disagreed with that conclusion and conducted a private autopsy last week. The results are not yet known.
Two days before Zahau's death, Shacknai's 6-year-old son fell down a staircase in the mansion and later died.
The 27-room Spreckels mansion was built in 1908 and originally owned by John D. Spreckels, owner of the landmark Hotel del Coronado and the San Diego Union and San Diego Tribune newspapers.
The Associated Press contributed to this story.