Adelaide woman jailed after obsessively stalking ex-boyfriend’s new partner.

Amy Kasehagen would wait, recording, hiding in the bushes filming Bronson Hayter leave for work.

She would follow her and photograph her.

She broke into her house and took images of the contents of her fridge and entered her bedroom and took a photo of her bed.

She watched and stalked her, soaking up every detail, what she wore, where she went, when she got her mail.

She learnt everything she could about her.

And then finally she planned to kill her – all because Bronson Hayter was dating Kasehagen’s ex boyfriend.

Bronson Hayter after the attack. Image via Nine News.

Yesterday the Supreme Court in Adelaide heard 32-year-old Amy Kasehagen hunted down her victim "like a rabbit in a spotlight".

Kasehagen had become obsessed with Ms Hayter and had her under extensive surveillance in the months leading up the attack.

In April last year it culminated when she broke into the home of the 28-year-old in Adelaide’s beachside suburb of Glenelg and tried to kill her.

The court heard that Kasehagen had become “consumed with jealousy” reports the ABC.

Supreme Court Justice David Lovell said Kasehagen’s surveillance of Ms Hayter was chilling, including photographs of Ms Hayter’s home and car, details of her work and notes written by Kasehagen debating whether to “kill”, “knock out”, “scarf choke” or “suffocate with bag” her former partner’s girlfriend.

The court released video surveillance taken by Kasehagen.

In it Kasehagen, who suffers from an eating disorder, hoarding disorder and a borderline personality disorder,  follows her victim, taking note of her day-to-day activities and narrating the scene before her.

As she walks up Ms Hayter's driveway, the 32-year-old says, ““I really don’t want him to have a valentine. That’s really cruel of me I know but he’s an absolute m----r f---er. I still love him, which is stupid of me.”

In another video she says, “Thursday night I'm assuming is when I want to do it.”

In one video she was standing outside Bronson Hayter’s house. She watches her leave for work and says “7.28 via the iPad she’s leaving for work. She’s dressed really f--king weird,”

The court also saw photographs taken by Kasehagen inside house’s interior, showing her Bronson Hayter’s bedroom and the inside of her fridge.

A photo of the inside of her victim's fridge taken by Kasehagen . Image via Nine News.

Kasehagen also wrote notes on whether she should try to kill her.

One note – a list says, “Kill Bronson - bitch deserves it”.

It then lists 'hammer', 'cuff' and 'suffocate'.

One note – a list says, “Kill Bronson - bitch deserves it”. Image via Nine News.

Another says if she were to knock the woman out, Kasehagen would “shatter her hands” and put “caustic soda in her eyes.”

In April 2015, she decides to strike, after deliberating what to do in her notes she has made her decision.

She would kill her.

A note found in Kasehagen's home. Image via Nine News.

Kasehagen broke into Ms Hayter's home and hid until her victim came home.

She then attacked Bronson Hayter, striking her 10 times with a hammer before trying to strangle her with a scarf, blocking her nose with her fingers and then attempted to suffocate her with a plastic bag.

Ms Hayter managed to escape to a neighbour's house when the phone rang and provided a brief distraction.

In sentencing Justice David Lovell said the attack was brutal, premeditated and terrifying.

“Whilst on the floor, you pushed her in the back and then struck at her with a hammer approximately 10 times.”

“You also tried to suffocate her by pushing a plastic bag into her mouth and you did this on at least four occasions,” he said.

Each time, Ms Hayter was able to pull the bag from her mouth, fighting off her attacker.

“What was a routine return home from work for Ms Hayter turned, in an instant, to a frightening and no doubt bewildering few minutes in a fight for her life.”

He said Ms Hayter was extremely fortunate to escape with her life despite Kasehagen’s “determined bid to end her life”.

“The attack on the victim was motivated by jealousy and hatred and could have resulted in her death had she not escaped,” he said.

Bronson Hayter outside court. Image via Nine News.

Justice Lovell said that evidence from Kasehagen’s friends that she was kind and helpful was confusing.

“It is clear that there must be two sides to your personality and it makes your behaviour towards Ms Hayter somewhat perplexing,” he said.

“There is no suggestion that you were not aware of the nature of your actions or that you were unable to control your actions at the time you attacked Ms Hayter.”

The Advertiser reports that during trial Kasehagen’s lawyer Craig Caldicott said his client was aware what she had done was wrong but had little insight into her offending because of her psychological background.

“It appears she can be a helpful, functional, terrific young woman and that’s why this particular offence is so out of character,” he said.

“Because of her psychological background she can’t express contrition or remorse.”

Justice Lovell jailed Kasehagen for 12 years, with a non-parole period of seven years.