A 51-year-old Buffalo Township man was arrested today on charges he sexually assaulted a woman last week at her home in Washington Township.

He also is accused of leaving two threatening messages on her telephone answering machine, state police said, after she reported him to police.

The suspect, Robert R. Gladd, who was wanted on an arrest warrant in the case, was picked up this morning at his home on Bryan Drive but not without incident, police said.

He allegedly struggled with officers and suffered minor injuries during his arrest. Trooper Ronald Kesten said he refused medical treatment.

Gladd is being held in the Butler County Prison on $100,000 bail. He faces several charges including three felonies in connection with last week’s alleged sexual assault.

Kesten said police also plan to file additional resisting arrest charges stemming from this morning’s incident.

Police began their investigation July 3 when the alleged victim contacted authorities to report being assaulted by the defendant the day before, according to court documents.

The Butler Eagle is not identifying the accuser due to the nature of the charges. She and Gladd knew one another prior to the suspected assault.

The woman told investigators that she invited the defendant to a get-together with her husband July 2 at the couple’s home.

She recounted that they ate, drank and lit fireworks that night before she and her husband went to bed. Gladd stayed overnight on the couch.

The next morning, documents said, the woman’s husband went to work while she and the defendant drank beer.

While drinking at the kitchen table, the suspect rubbed her leg twice, she said.

She told Gladd to “have respect” because she was “happily married,” documents said.

The woman estimated that she consumed 8 to 10 beers before taking a nap around 10 a.m., documents aid.

“About 25 minutes later,“ according to police affidavit, “she woke up to Gladd naked and (sexually assaulting her).”

She told police that she screamed, kicked the suspect and told him to leave.

Trooper Brian Palko that same day tried unsuccessfully to contact Gladd.

On July 4, the woman notified police that the defendant had left threatening messages on her phone’s answering machine that night.

Palko later listened to the messages in which he “apologized for his actions and blamed alcohol,” the trooper said in his criminal complaint.

But Gladd in the recordings also warned the accuser and her husband, documents said, that if they “didn’t get the cops (off) his back that there would be trouble.

District Judge Lewis Stoughton arraigned the suspect on felony charges of aggravated indecent assault, sexual assault and intimidation of witnesses or victims, and a misdemeanor charge of indecent assault.