A Houston science teacher allegedly gave test answers and perfect grades to his student during their months-long sexual relationship, a criminal complaint revealed.

Spring Branch Independent School District teacher Stephen Griffin, 46, is facing felony charges for an improper relationship with an 18-year-old student, according to a complaint filed in Harris County District Court last month. He has been released on $5,000 bond since his Dec. 7 arrest, court records show. 

"There's been no evidence of this whatsoever and we deny the charges," his attorney, Justin Harris, told Fox News Digital on Monday. "Mr. Griffin has been a model teacher throughout his career and this has blindsided everybody. We have some trails that we're going down that might explain where these allegations might be coming from.

"Generally when these things happen, what you read in complaints and what actually ends up happening are usually night and day from each other. They're on the same planet, but they're different parts of the same day. We're waiting to see the evidence in the case. At this time it's just allegations. If you believe the state's allegations on their face, this is not a sexual assault case – this was a consensual act between two adults."

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Griffin's 18-year-old student told Spring Branch ISD Police that she would meet her science teacher at a hotel and, later, at his apartment in the 2022 and 2023 school year. 

The teacher was working at Memorial High School at the time and in the process of divorcing his wife, according to the complaint. 

Texas Penal Code 21.12 classifies an improper relationship between an educator and student as a second-degree felony, whether the student victim is legally a minor. It is punishable by up to 20 years in prison and $10,000 in fines. 

The student's mother reportedly brought their relationship to administrators' attention around Nov. 30, according to the complaint. Her daughter would share incriminating text messages between herself and Griffin with Spring Branch ISD Police later that day. 

About a year earlier, on Sept. 23, 2022, the unnamed female student emailed Griffin asking to eat lunch in his classroom during his off period. The teacher emailed her his personal cellphone number after the meeting, telling her they had "similar backgrounds" and that he was available if she ever needed help or someone to confide in.

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The pair texted back and forth for a few months, the complaint shows. In November, the student met with Griffin at the Staybridge Suites Hotel, where they had sex, according to the complaint.

They would continue to meet there, she told police, and once exchanged oral sex in his classroom. On one occasion, she and Griffin allegedly had sex in the back of her car behind a restaurant in Houston. 

At that point, the student recalled, the teacher began giving her test answers in advance and 100% scores on all of her assignments. Griffin allegedly gifted her his gray staff jacket and a candle that smelled like his cologne. 

Their relationship ended midsummer 2023, the student said – Griffin allegedly told her to stop contacting him because he was trying to reconcile with his wife. 

A Spring Branch ISD digital forensic technician then took the student's phone to scour her Snapchat and Signal accounts for correspondence with Griffin. 

The complaint showed one Snapchat message from Griffin on an unknown date read: "We need to talk. I miss you. Can we talk? I'm suicidal right now. Call me. Ok babe. This is how it's going to be? Don't do this, call me. Can we talk in person? Want money? I'm about to kill myself. Please call me."

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It is unclear whether Griffin is still employed at Memorial High School – his name is still listed in the school's staff directory on its website. 

Griffin's employment status was not immediately available from Spring Branch ISD officials.

"(This is) a personnel matter involving a criminal investigation. The district cannot confirm the identity of individuals involved at this time," Spring Branch ISD told ABC 13 last month. 

Griffin's next court date is scheduled for Feb. 28, per online court records.