Planned explosions forced the helicopter down into the Santa Clara River, which the three actors were crossing.
In 1970 Maxwell married attorney Ervin Roeder, who was 21 years her senior.
After Blue Hawaii, she did make a couple of film appearances.
The shooting happened in the afternoon in front of a building and looks to have never been solved.
One woman Barbara Colby was apparently randomly gunned down in a parking garage and one man burned to death after falling asleep with a lit cigarette Jack Cassidy.