A man is in jail after an alleged sexual assault at knife point early Saturday morning. Waite Park Police say a woman asked for a ride home from Sauk Rapids around 5:15a.m.  She got a ride home from 41 year old Tracy Thompson of Waite Park.   Thompson took the victim to a garage on the 300 block of 2nd Avenue South. While in the garage, Thomson allegedly threatened the victim with a knife and sexually assaulted her. Thompson was arrested and is held for court on charges of 1st degree criminal sexual conduct.