The suspect accused of fatally shooting four people at a Montana bar and who remains at large struggled with mental health issues, but was denied services from agencies that were supposed to help, according to his niece.

Officers are "unrelenting in their pursuit, working around the clock" to find him, Montana Gov. Greg Gianforte stressed at a news conference on Tuesday. "Rest assured, our brave men and women of law enforcement aren’t giving up."

The victims killed during a shooting at The Owl Bar in Anaconda, Montana, range in age from 59 to 74, Montana Attorney General Austin Knudsen said in a news conference Sunday.