A Tennessee preacher and teacher’s assistant has been accused of binding and then raping one of the teenage girls from his school, though his defense attorney says he is innocent and “has not committed any crime.”

Law enforcement alleges otherwise: Officials say Mike Ulmer, 53, picked up the victim, 18, from Chester County High School on Feb. 16 and brought her to his home in Henderson, Tennessee.

Ulmer serves as a pastor at Bethlehem Baptist Church in Henderson, and court records show the victim was paid to clean his house.

She is a student at Chester County, where Ulmer also worked, though a source tells PEOPLE he was suspended from his teacher’s assistant position on Feb. 17, moments before he was taken into custody.

The day before Ulmer was arrested, authorities allege he directed the teen to do some cleaning in his office, which is contained within a detached garage on his property.

The victim told investigators that Ulmer allegedly used a rope to bind her wrists in the garage. He then wove the rope through a hook in the ceiling, she claimed, which prevented her from escaping.

According to court records, she told police Ulmer allegedly sexually assaulted her after she was bound.

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He has been charged with rape, sexual battery and assault, to which he has pleaded not guilty.

The assault charge was filed on Thursday, after the same victim told police she had been abused by Ulmer nearly four months ago.

Court documents allege that in November, he asked the girl if he could “put his fingers in her mouth” as he was driving her home.

She refused, but that allegedly didn’t stop Ulmer: Authorities claim he jammed his fingers into the girl’s mouth before pulling over behind a lumber yard, where the victim said he “was holding her head down in his lap and forced her mouth open.”

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Investigators say the victim recorded the alleged incident on her cell phone and that Ulmer can be heard in audio from the incident ordering the girl to open her mouth.

The girl can also allegedly be heard on the recording asking him to stop.

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Ulmer has been released on $250,000 bond and is due back in court on May 9.

Neither Ulmer’s church nor the local school district responded to requests for comment. His defense attorney, Mark Donahoe, tells PEOPLE he intends on vigorously fighting the charges.

“We maintain that Mike did nothing wrong,” Donahoe says.