"I'm not a monster": Teen who murdered her mother and stepfather speaks out for the first time.

It was March 7, 2015. A day after her 17th birthday and she was home with her family – her mother, three younger siblings and stepfather – in their Wisconsin home in the U.S.

Ashlee Martinson fired two shots with her stepfather’s shotgun. The first hit her stepfather, Thomas Ayers, 37, in the neck. But she wasn’t sure he was dead. The second shot was straight to his head.

She didn’t stop there.

Martinson ran downstairs where she saw her mother with a decorative knife in her hand. She grabbed the knife and stabbed Jennifer Ayers, aged 40, a total of 30 times.

Two dead bodies. Blood everywhere. Martinson locked her younger siblings in a bedroom and fled.

She was arrested in Indiana, where she was staying with her boyfriend. She pleaded guilty to second-degree homicide and received a 23-year prison sentence.

Now, in an exclusive interview with Crime Watch Daily on Tuesday, Martinson (now 18) has told her story for the first time.

“I’m happy,” Martinson said. “I know that sounds crazy, because I’m in prison, but I feel like I’m free. I can wake up every day and know that I am safe.”

Martinson describes a childhood filled with dark and relentless abuse at the hands of  her mother’s boyfriends.

One man, she claims, raped her when she was nine years old. “He was extremely abusive,” Martinson told Crime Watch Daily. “That man, that man took everything from me. She [her mother] would send him in to tuck me in at night or to give me a bath. She knew. She knew what was going on.”

Ayers was no better, Martinson said. Although he didn't hurt her personally, she told Crime Watch Daily he often abused her sisters because that "was the way he knew he could hurt me".

Ayers would hit the girls "very hard" with "a think belt and his hand", according to police reports. Martinson's sisters told authorities Ayers had choked them and punched one of them in the face, giving her a black eye. Court documents showed Ayers had been accused of assault, kidnapping, child enticement and party to the crime of sexual assault of a child younger than 14. He had several prior arrests and convictions.

"I woke up this morning to my stepdad beating my mum," Martinson posted to her Facebook page the day before the killings. "I can’t take it anymore, he’s gonna kill her if she doesn’t leave soon and I don’t want to be around when that happens."

The next day, Martinson argued with her mother and stepdad. She was meant to move out, to live with a friend, but Ayers stopped her. Initially, she grabbed the gun with the intention of killing herself.

"I was sitting on my bed. I even had the end of it in my mouth, playing with the trigger," she told Crime Watch Daily. "Then I heard my stepdad."

"I was scared of him. I am messing with his gun - one of his precious belongings. And I thought he was going to snap on me. And I just reacted. ... I raised the gun and I pulled the trigger."

"I start running down the stairs," she continued. "I was on the first landing and that's when I saw my mum. She ended up grabbing this decorative knife that was on a shelf and the next thing I knew the knife was in my leg."

Martinson "blacked out". She told Crime Watch Daily she was all of a sudden held captive by a "movie reel" of her worst memories playing in her head.

"Memories of all the bad things that happened to me, that she [her mother] put me through," she said. "And I remember stabbing her once, then twice, and then I black out and the next thing I knew there was blood everywhere."

"I'm not a monster," she continued. "I never meant any of this to happen. It doesn't make it right, what happened. But I was just a girl, an abused girl, who was forced to make a really bad decision.

"I'm not the monster that they portrayed me to be."

Martinson was portrayed as deeply disturbed, a notion that was fuelled by her blog - written under the pseudonym "Vampchick" - that described killings and blood-lust and torture.

One post, published five days before the murders, read:

“Rushing through the woods late at night. Deep into the darkest corner where the agonising screams cannot be heard. Walking into a small cabin. Marvelling at the sweet horrors of blood that I thirst for. I then take the next victim who is unconscious. I tightly bind them to a low table.

“Awaiting them to wake once more. I clean the dry blood off my tools from a previous session. The last body has been disposed of just hours before, yet I have not been satisfied with the pain, agony and blood. I bend down as they start to wake.

“‘Welcome to hell,’ I whisper in her ear. ‘Never again will you see the light of day’.

The blog has since been taken down.

Professionals who interviewed Martinson after the killings described her as suffering severe depression and post-traumatic stress disorder, The Washington Post reported earlier this year.

Now, looking forward, Martinson hopes to build a relationship with her siblings.

"I hope that one day that they can come to me and I can tell them what really happened. The truth," she told Crime Watch Daily. "Because I do want a relationship with them. I miss them so much. "