An Austin firefighter is under investigation after allegations that he used his job to lure a stranded woman into his marked city truck before sexually assaulting her, a new search warrant obtained by KVUE's and the Austin American-Statesman's Tony Plohetski confirmed Tuesday.

That firefighter -- who has not been charged -- is now off the job while the investigation continues. KVUE News is not naming the firefighter because he has not been charged.

The investigation stems from statements from a woman who came forward earlier this month to report her allegations which she said happened in March. The Austin police special investigations unit and Travis County prosecutors have opened a full investigation.

The details are described in a new search warrant for the firefighter's truck, which detectives said may have important clues such as DNA evidence.

According to the warrant, the woman was at Interstate 35 and St. Elmo Road when a passenger in her car got angry with her, yanked the keys out of the ignition and ran away, leaving her stranded. She said the firefighter pulled up behind her with emergency lights and got her keys back from the woman at a nearby Shell gas station. The warrant goes on to say the firefighter asked the woman to get in his city car, then drove her to a building where she claims he assaulted her.

The document said the woman does have a pending criminal charge for a crime that is not identified. She reported to police that the firefighter told her "that she needed his help and that if she knew what was good for her, she would allow him to help her because she was in a lot of trouble ... You're going to help me relax, and I'm going to help you."

Plohetski has reached out to that firefighter through the union, but he declined to comment. His attorney declined to comment as well.

Fire Chief Rhoda Mae Kerr told Plohetski in a statement that she is reserving judgment, but that her employee -- like anyone else -- is innocent until proven guilty.

This is the second criminal investigation involving a member of the Austin Fire Department. Last week, KVUE reported that a firefighter is under investigation for allegedly putting recording equipment in the women's locker room of a fire station. That case remains under investigation, as well.