NT Police officer acquitted of perverting justice

A Northern Territory Police officer has walked free from court after being acquitted of pressuring his former partner, who was also a police officer, to withdraw an aggravated assault charge against him.

Karol Jarentowski stood trial in the NT Supreme Court on a single count of attempting to pervert the course of justice before jurors returned their unanimous not guilty verdict this morning.

It took the jury just three hours to clear Mr Jarentowski of the allegations, including that he sent the woman a series of text messages threatening her access to child support.

The court heard the messages read: "If I lose my job, I'm on the streets" and "without you there is no prosecution".

"If I get found guilty, I'm out of a job and no child support for you," one message read.

In a separate phone call, prosecutors alleged Mr Jarentowski told the woman to "act like an adult" and offered to make concessions in a custody dispute between the pair if she agreed to drop the charge.

The court heard Mr Jarentowski had been charged with aggravated assault and was subject to a domestic violence order prohibiting abuse, coercive control and intimidation after he threw two T-shirts at his former partner.

The incident happened during a disagreement over parenting at their child's tennis game a few weeks before the messages began and he later pleaded guilty to the assault charge.

The ABC has chosen not to name the former partner to protect her identity.

'Not good policing'

Yesterday, the police officer in charge of the case, Katherine Lumsden, took the stand and denied under cross examination infecting the evidence of a key witness.

The court heard Ms Lumsden sent an email to Mr Jarentowski's former partner containing both her and her mother's written statements and received amendments to both documents through text messages from the former partner.

"It's not ideal because it creates a risk that each of their evidence, each of their recollections of what happened, is affected by the other," defence lawyer Ben Fernandez told the jury.

"That's not good policing, is it?"

In her evidence, Ms Lumsden conceded that avoiding contaminating witness evidence was crucial as an investigator and that the "circumstances were not ideal".

However, she said she "had conversations in the past about not discussing the matters" and assumed the woman's mother had "issues with technical literacy" and would need help with her emails.

The court heard Ms Lumsden sent an email to Mr Jarentowski's former partner, saying: "I've also attached your mum's statement."

"I know it will be very tempting, but if possible, refrain from reading each other's statement or talking about any possible differing versions," she wrote.

In his closing address yesterday, Crown prosecutor Lachlan Macdonald noted both women had denied reviewing each other's statements, and submitted that the jury could easily infer from the evidence that Mr Jarentowski had deliberately sought to "frustrate" criminal proceedings.

He pointed to police body-worn camera footage captured at the time of Mr Jarentowski's arrest and played to the court in which he could be heard telling another officer he thought the assault charge was "bullshit".

Complainant 'assumed the worst'

In summing up the case, Chief Justice Michael Grant said the Crown alleged Mr Jarentowski "cajoled and coerced" the woman in an attempt to compel her to withdraw her complaint "to avoid criminal responsibility for his conduct".

But in his closing address, Mr Fernandez urged the jury to apply their common sense in assessing the evidence.

He said Mr Jarentowski was simply intending to "discuss the matters" with his former partner and never intended to pervert the course of justice.

"You've heard [Mr Jarentowski's former partner] describe those messages as an attempt … to manipulate her," he said.

"[She was] stretching her imagination and assuming the worst of Mr Jarentowski."

Mr Fernandez pointed to other messages in which his client said words to the effect of "Let's work it out, I fell in love with you, let's move on", saying it left doubt about his intent and amounted to nothing more than lawful persuasion.

"[When he said] 'please let's talk, I'll lose my job' … that's an objective truth, if he loses his job, he'll lose the child support,"