Tragic news out of the North Texas basketball program -- assistant coach Nelson Haggerty has passed away after a single-car crash Friday morning. He was 47 years old.

Haggerty was part of the coaching staff that helped lead the Mean Green to their first-ever NCAA tournament win last month ... when #13 North Texas beat #4 Purdue 78-69 in the first round on March 19.

Law enforcement officials in Texas say Haggerty was driving on Highway 380 near the city of Decatur in Wise County around 2:30 AM Friday ... when his car went off the right side of the road and hit a culvert, according to local reports.