A former police officer accused of six months of incestuous sex attacks on a 15-year-old girl allegedly gave her herpes and made her believe they were boyfriend and girlfriend.

Troy Estree, 46, allegedly repeatedly sexually assaulted his young relative in 2014, including while he was on duty.

Estree, who was a cop in Emmett Township, Michigan, could face life in prison if he is convicted.

Troy Estree, 46, is accused of six months of incestuous sex attacks on a 15-year-old girl that allegedly gave her herpes and made her believe they were boyfriend and girlfriend

His alleged victim, who is now 17, gave testimony for five hours as she detailed the horrific abuse she claims to have suffered at the hands of the police officer.

She said that her relationship with Estree started out as meetings in public but soon she was invited round to spend time at his house, which he shared with his wife and two children.

She told the court the alleged abuse started awhile she was sat on a sofa with Estree, watching an episode of the comedy cartoon show Family Guy, KHOU reported.

'It started with him touching me up my leg and closer to my thighs and then my private areas,' she told assistant prosecutor Michael Stein.

'I didn't know what to do. He started rubbing my thighs and up to my vagina. I didn't know what to expect, and I didn't want to let him down,' the teenager said.

Estree is said to have given the girl a cell phone and they began messaging each other. The girl started staying overnight at the house and the former cop would give her alcohol, the court heard.

They were watching another episode of Family Guy on another night when Estree pulled down her shorts and had anal intercourse with her, the girl said.

She said: 'I don't remember what he said, but he was probably kissing my neck. I said I didn't want to do it anymore. I felt like trash. He said OK.'

The teenager said they had oral sex a few weeks later and she 'blocked out' her thoughts to get through it.

However, she began to 'enjoy' the relationship, which she considered dating rather than a sexual relationship between relatives, the jury heard.

Estree, who was a cop in Emmett Township, Michigan, could face life in prison if he is convicted

The girl described several more alleged sexual assaults, including on the trunk of his squad car while he was on patrol.

She also detailed further assaults on a park bench, on a construction site and in his basement.

'I thought it was normal,' she said. 'It was like a relationship thing. Now I know I had sex with (him), and it destroyed a whole family. It felt good. I had not had sex before and it felt good. I saw him more as a friend,' she told the court.

'We both gave each other a look and then there was caressing and kissing and touching each other. It felt more like a boyfriend. I called him "Bro".'

When she was questioned by police six months after the alleged assaults began, she tried to 'protect' Estree 'because I loved him', she said.

She lied to investigators to start with, but Michigan State Detective Sergeant Heather Johnson, who was interviewing her, refused to believe her.

Det Johnson told the girl that she would phone everyone in her address book and tell them that she had herpes unless she admitted having sex with Estree, the girl said during questioning by defense attorney Keeley Heath.

The then 15-year-old had earlier been to a doctor and was diagnosed with type 1 herpes, which is often transmitted sexually, the court heard.

The jury was told that Estree has type 1 and type 2 herpes.

The girl said she started to cry during the intense police interview. 'I guessed she already knew. I knew she knew I was having anal sex with [Estree],' she said in court.

She had earlier said she was having sex with a man called Brock, but told the court she 'made it up because I didn't know what else to do to cover up for [Estree]'.

Estree pulled down the girl's shorts and had anal intercourse with her while they watched an episode of Family Guy, the girl said

Two friends of the girl, Katherine Reed and Timothy Annarino, told the court on Thursday that they were told the girl was being sexually assaulted by Estree before police became involved.

Miss Reed, 17, said she was a close friend of the girl and that she was told the jury how he 'would do things to her', the Battle Creek Enquirer reported.

'He would kiss her. She was very confused about that,' the friend said.

Miss Reed said the girl told her that Estree kissed her but it escalated to anal sex.

'It became more than kissing,' she said. 'They were taking off clothes. She said he helped her unhook her bra and get her pants down and then she said he put his penis in her butt.'

Miss Reed said the girl 'enjoyed' spending time with Estree and told her she was not allowed to tell anyone about them.

The friend also told the court that the girl told her she was washing dishes when Estree pulled down her pants and had anal sex with her.

She also spoke of another assault on park bench when he was in police uniform.

The girl told the court she thought of Estree (pictured) as her boyfriend, rather than a relative

Miss Reed told the court that the girl said Estree sent a naked photograph of himself to her.

The friend said she felt 'foolish' for not telling the police but did not want to lose a friend.

Mr Annarino did not know the girl personally but was friends with a fake Facebook account she had set up under a different name.

He told the court that he advised her to go the police after she told him Estree 'was doing bad things to her'.

'She told me how he touched her vagina and she told me he was a cop in the Battle Creek area. I told her she should contact police,' he said.

Detective Sergeant Paul Gonyeau, from Michigan State Police, told the court that he inspected cell phones seized from the girl and Estree.

He said Estree's phone had been wiped of text messages but records given to police by the network provider showed 1,900 text messages were sent between the former cop's phone and the girl between May and August 2014.

Det Sgt Gonyeau read some of the texts and Facebook messages to the court.

One, from Estree, said: 'I failed you and you make it feel like it's your fault.'

The girl replied: 'I am used to this. This is filth. It is wrong on so many levels.'

Another message read to the court showed the girl saying: 'When you first touching me I said OK. I didn't know what to do. Now I am used to it. I think it is normal. I feel like filth for the longest time. We are screwed up and this will never be normal again.'

She is later said to have added: 'I kind of feel like filth and am kind of afraid of you.

According to the Battle Creek Enquirer, Defense attorney Ms Heath told the court earlier this week that the girl 'is crazy'.

'She was brought to a mental health facility with magical thinking and odd thoughts and short-term memory loss and she might not be oriented to reality,' Ms Heath said.

Ms Heath added that many of the sexual assaults the girl described were 'unbelievable' because they were 'high-risk situations'.

Prosecutor Stein told the court the deleted texts messages and both Estree and the girl having herpes were evidence that the assaults did happen.

Estree was fired from the police after his arrest. He is charged with nine counts of first-degree criminal sexual conduct with the girl, who was underage and is related to him. He denies the allegations.

In a separate case, Estree is also accused of raping his adult niece in hot tub.

According to Fox 17, he allegedly asked her to show him her breasts while he was naked in the hot tub before forcing her to have sex with him.