"To be close to the person who was with him last is comforting to me," Regina Crain said.
Crain's father also attended the event, along with Riverside Police Chief Sergio Diaz and Lt. Larry Gonzalez, the watch commander on duty when Crain and Tachias were attacked.
Dorner went on a rampage after he was fired by the Los Angeles Police Department for filing a false report.
He killed four people and wounded Tachias before committing suicide Feb. 12 after he was cornered in a mountain cabin near Big Bear Lake.
Authorities surrounded the cabin after a wild chase that began when Dorner tied up a couple and stole their car, crashed it and carjacked another vehicle at gunpoint, then crashed that one and fled to the cabin.