The father of a 19-year-old New York man who was beaten to death during a church counseling session has pleaded guilty for his role in the attack, which also injured another son.

Bruce Leonard pleaded guilty to assault Wednesday in Oneida County Court, where he was scheduled to go on trial on a more serious murder charge Thursday.

As part of the plea, Leonard will have to testify against his step-daughter, Sarah Ferguson, who's among seven others awaiting trial for the October attack that killed Lucas Leonard and injured 17-year-old Christopher Leonard. Authorities have said the boys had discussed leaving the secretive Word of Life Church.

Ferguson's murder trial is scheduled for Thursday. The others face trial in September.

Bruce Leonard is expected to be sentenced to a total of 15 years in prison.