A Summit Township man accused of fathering four children with his daughter exchanged his right for a preliminary hearing for a sentencing offer from the Butler County District Attorney’s office.

If the man, 56, pleads guilty to all of the charges, which includes 71 counts of rape, prosecutors will recommend that he be sentenced to 15 to 30 years in state prison.

The man, who is not being named to protect the daughter’s identity, is not bound to accept the offer, which was presented Monday in the office of District Judge Pete Schaffer.

However, defense attorney Joseph Smith said his client’s decision to waive his preliminary hearing in exchange for the offer was based on the alleged quality of evidence prosecutors have and the potential for significantly longer, mandatory sentences if the defendant were to be convicted at a trial.

Among the alleged evidence is positive paternity tests of the man to the accuser’s four children, according to court documents.

Prosecutors have asserted the defendant began assaulting his daughter in 1992 when she was 12 years old. Court records allege the defendant used violence, threats and alcohol to force the victim to submit.

During the years of suspected sexual abuse, the accuser delivered children in 1994, 1996, 1997 and 2000, all in Allegheny County. The eldest child died last year of natural causes.

Court records indicate the man also took numerous photographs of the accuser during the assaults.

Investigators have not said why the woman disclosed the allegations Aug. 26 to Butler County Children and Youth Services.

Both the accuser and the defendant appeared in the courtroom Monday, but neither spoke.

In addition to rape, the defendant faces charges of involuntary deviate sexual intercourse, statutory rape, indecent assault, aggravated indecent assault and incest.

He is in the Butler County Prison on $500,000 bail.

Assistant District Attorney B.T. Fullerton acknowledged it is slightly unusual to exchange a plea arrangement offer in exchange for a defendant’s waiver of a preliminary hearing, but he refused comment.

It is more typical for a defendant to waive his preliminary hearing rights for a reduction in bond or charges.

In another unusual move, spectators entering the courtroom Monday were obligated to pass through a metal detector. Court officials said there was no particular threat or request that prompted the additional security.

The defendant is scheduled to appear Dec. 17 for a formal arraignment in the Butler County Court of Common Pleas.

If he chooses not to enter the plea arrangement that has been offered, the case will take a normal course through the system, which will include a number of hearings leading up to a trial or plea.