Michigan State University has maintained ties to a prominent volleyball coach for decades after he was publicly accused in 1995 of sexually abusing and raping six underage girls he trained.

Letters obtained by The Associated Press from accusers' advocates reveal the school has been pressured for at least a year to sever its relationship with Rick Butler.

Butler runs suburban Chicago training facilities that have been a pipeline for top recruits, including to MSU.

MSU has been reeling from the scandal involving a gymnastics doctor, Larry Nassar, who molested young athletes.

The university said in a Monday statement that Butler is currently "not affiliated with MSU." But it didn't address other questions put to it, including when any affiliation might have ended.

Butler was never criminally charged. He denies sexually abusing anyone.