Davell Roby had six of his career-high-tying 16 points in overtime for the Billikens (11-16, 3-11 Atlantic 10), including a driving layup and a corner 3 for the first five points of the extra period.
Roby made 1 of 2 free throws with 23.5 seconds and Crawford pushed the lead to 66-62 on the first of his pair of free throws.
Jordan Price's pair of free throws with 25.8 seconds left in regulation tied the game at 58, and Achraf Yacoubou missed a 3-pointer for Saint Louis at the buzzer.
Yacoubou had 13 points and Crawford 10.
Price led the Explorers with 22 points and Zack added 16.