GRAND JUNCTION, Colo. (KKCO) -- A newly selected jury listened to opening statements in the case against a former Grand Junction police officer and firefighter

Eric Janusz sat calmly in a Mesa County courtroom as the prosecution and defense started to make their case for and against him.

The prosecution began by depicting Janusz as a man of the law who took advantage of the victim-- who was 15-years-old when their alleged sexual relationship began.

The defense countered by saying "the victim tells twists of lies," arguing that Janusz never had underage sexual encounters with the victim.

Janusz and the victim met while he was responding to a call regarding the victim's runaway brother. However, the defense team argues that a sexual relationship did not occur until 2004 when the victim was of legal age.

The prosecution and defense both recognized the sexual relationships Janusz and the victim had in 2004 and later in 2011.

In 2011, the prosecution says Janusz wasn't forthcoming about having a girlfriend and threatened the victim if she told his girlfriend about the encounters, saying "he'd bury her in the desert for all of this."

According to the defense, in 2011, the victim became jealous of Janusz's girlfriend, harassed and threatened him via text message and showed up at Janusz's home.

Now the prosecution has the job of proving Janusz is guilty of an alleged crime committed over a decade ago. Witnesses also began to take the stand Tuesday, and they will continue Wednesday.

Janusz is facing four counts of sexual assault on a child by a person in a position of trust and one count of sexual assault as a pattern of abuse.