Ruddelle admits she is responsible for Ngapera's death, but denies the charge of murder.
Rather, she claims she acted in self defence trying to protect herself and her teenage son, and was suffering from social entrapment - effectively battered women's syndrome - after a lifetime of domestic violence - including at the hands of Ngapera.
The Crown - this was drunk, angry murder
Crown prosecutor Yelena Yelavich said it was "inevitable" jurors would have feelings of sympathy for Ruddelle and prejudice against Ngapera given his earlier violence and abuse towards her.
"There is no dispute that there has been domestic violence ... that prior history is only one aspect of what you need to take into account," she said.
"It is not a defence to murder or to manslaughter to say that your partner has previously been violent against you.
"The Crown's case remains the same as it was when it opened the case ... the defendant was not defending herself or her son when she stabbed her partner ... The Crown says that the actions of the defendant were simply not reasonable in the circumstances as she believed them to be.
"The defendant's actions were excessive. When the defendant stabbed Mr Ngapera, she intended to kill him, or at the very least she intended to cause him bodily injury."
Yelavich said being abused by a partner did not give anyone the right to take their life.
The jury have heard from more than 40 witnesses about the night Ngapera died - the lead-up, and aftermath.
Witnesses included Ruddelle's son, who tried to revive Ngapera, and the accused herself.
Experts on domestic violence and social entrapment were also called and jurors heard Ruddelle was suffering symptoms of PTSD.
The defence yesterday revealed Ngapera has previous convictions for violence against two other women.
As when he would abuse Ruddelle, Ngapera had been drinking before each assault.
Yelavich told the jury while the expert commentary around domestic violence was
helpful, it was not relevant to Ruddelle's case.
"Yes there was violence and intimidation but typically in the context of Mr Ngapera drinking alcohol and not in a pattern of coercive control ... [Ruddelle] certainly did not feel
trapped in the relationship," she said.
"Alcohol abuse seems to be at the root of this abuse ... the relationship was dysfunctional, at times they were arguing but there was a loving side.
"It has to be said that Mr Ngapera cannot be described as an angel."
Yelavich said Ruddelle often called police - 16 times during her relationship with Ngapera - when she felt endangered.
She was also granted a protection order but applied to have that discharged several months before Ngapera died.
Yelavich said that spoke to Ruddelle not feeling threatened or unsafe.
"The pattern of violence ... became less severe and more infrequent," she said.
"In the period of time leading up to [the death], the defendant was well equipped with a number of strategies to deal with Mr Ngapera."
Those strategies including calling 111, leaving the house and asking Ngapera to leave.
Yelavich said the Crown did not hold Ngapera up as a "model partner" and there was no suggestion he was not at fault.
But the trial was about Ruddelle's response the night he died - and there were a range of "alternative" options for her that night.
She said on the night Ruddelle was "drunk and angry" and aggressive, emboldened by alcohol.
Ruddelle had an "easy" route out of the room where the alleged murder happened.
But she stayed.
"This was not a situation where the defendant was frozen to the spot ... despite Ngapera being close enough to touch her, he did not lay a finger on her ... not trying to touch her ... not even raising a hand," said Yelavich.
"There was no physical violence ... the Crown says [Ngapera] posed no physical threat to her.
"At no stage did Mr Ngapera threaten her ... she knew [he] was unarmed ... the very notion that the defendant might suddenly attack her or [her son] would be laughable if what happened next did not have such tragic circumstances."
Yelavich said Ruddelle acted quickly to catch Ngapera by surprise rather than on instinct to protect herself.
"She did so deliberately and intentionally," she said.
"Grabbing the knife ... the first stab into the chest, a vulnerable part of the body ... removing the knife from his body ... stabbing him again.
"And don't forget that one of those stabs involved substantial force ... fast, but intentional.
"The evidence does not support the claim that the defendant was afraid ... he had not even made a show of force."
She said Ruddelle's defence was "pure fiction".
"Perhaps she saw this as an opportunity to get Mr Ngapera back ... for karma.
"You can be sure [she] was not acting to defend herself when she stabbed Mr Ngapera."
Yelavich said in a case of "lethal force" Ruddelle would have had to be under "dire and imminent" threat of danger, and have no other options readily available.
"You can be sure that the defendant's actions were not defensive ... they were unreasonable," the Crown prosecutor posed.
"You can be sure that the force used was not reasonable.
"A murder is still murder, even if it was impulsive, unplanned and immediately regretted.
"When you consider Miss Ruddelle's actions ... the logical conclusion is that she intended to kill Mr Ngapera ... significant harm was not only likely, it was inevitable.
"The Crown says she was not acting in self defence ... the Crown says that the defendant is guilty of murder."
The defence - a desperate act by a woman in fear
Defence lawyer Shane Cassidy started his closing by revisiting the time Ngapera had tried to choke Ruddelle and the various times he had told her he would kill or murder her.
"How many times does someone need to be told that they are going to be killed before they start to believe that that is a real possibility?" he asked the jury.
"The reality of the situation is that once you've been strangled, once you've been subjected to force of that level, nothing more really is required in terms of physical enforcement - a threat is enough.
"Being held against a wall with someone's hands around your throat, believing you are going to die and just pleading for that to stop.
"When something like that happens it doesn't need to happen again ... a simple threat is enough."
Cassidy painted a picture of a battered and traumatised woman living in fear and under the coercive control of her abusive, violent and intimidating partner.
Not only was she scared for herself - she was worried for her children, particularly her 14-year-old son who lived with her.
Cassidy reminded the jury about the 16 times Ruddelle called police to help her and about the protection order she obtained against Ngapera.
"How many times does someone need to call police and not have anything done?" he said.
"The law does not require you to retreat if there is clear and present danger.
"You are also allowed to preemptively strike if you anticipate you are about to be hurt - to strike another person to protect yourself or another.
"You don't have to wait there and take what you think will come, you are allowed to protect yourself.
"If you act defensively you are not guilty of what would otherwise be a criminal offence ... you are not legally responsible for causing harm to another, or death if you are protecting yourself from serious harm or injury."
Cassidy told the jury his client was "not thinking about much at all" when she stabbed Ngapera.
"She wanted to protect her son, and that was the only thing going on in her mind," he said.
"Causing harm to another person when you are fighting for your life is a byproduct of what you are doing, it's not the reason you are doing what you are doing.
"It doesn't matter what the subjective feelings are - as long as you acted defensively.
"When Karen used the knife, causing his death or turning her mind to the consequences, wirer not the thoughts that she had - the singular thought that she had was for her son."
Cassidy said that was clear in the 111 call, where Ruddelle could be heard in the background extremely upset.
"Instant regret - and it's instant because it's not what was intended," he said of Ruddelle's reaction.
"Instant regret because the consequences were not intended ... [her] son was safe, but the man she loved was dead.
"It's the devil and the deep blue sea, the choice that she was placed in."
Cassidy said men strangled women "to show that they are capable of killing".
Further, Ngapera told Ruddelle and previous partners that he had murdered someone in Australia and described other incidents where he "could have killed" others if he'd chosen.
He said in the 111 calls that followed there might not have been any physical violence - but "there didn't need to be".
"There was a pattern ... reminding 'I can kill' and telling 'I will kill',' he said.
"Joseph was letting Karen know in no uncertain terms that he could not only commit violence against her, but against others.
"It would be absolutely and utterly inconceivable that none of this was going through Karen's mind when [her son] appeared [on the night of the murder] and shoved Joseph.
"I suggest also, wrapped up in those emotions, the memories of the repeated threats to kill ... being struck quickly twice, thinking she was going to be killed ... [her son] must have been within punching range."
Cassidy said he wanted to address the jury about what the trial was about from Ruddelle's perspective.
He said it wasn't so much about coercive control or social entrapment.
In fact, she did not know about either concept before trial.
"What this trial is about for her is her love for her 14-year-old trial - that's it," Cassidy said.
"It is about the things people do for the people they love… the choice that she had to make."
Cassidy said Ruddelle genuinely loved Ngapera and wanted to help and heal him.
"Karen was also conditioned… to behave in certain ways - to protect them… to accept violence.
"And in the process of accepting violence, there were times where she put her own safety at risk."
He said not reporting much of the violence Ngapera meted out to her was symbolic of that.
"She didn't want to get Joseph to get in trouble, she just wanted the violence to stop… she just wanted him to stop being violent.
"Her plan was to love him... to heal him.... to stay with him through the good and the bad... she placed her safety at risk at times."
Cassidy said Ngapera had his own deep-seated issues over and above his drinking.
He had learned that an "effective" way for him to assert control over women was "to be violent".
"He had many, many endearing qualities, he was extremely generous," he said.
Cassidy said it was "simply unrealistic" for Ruddelle to go and call police or "leave".
Her son had never been present or involved in the violence before.
"It was different... the risk was elevated," he said.
"No, she couldn't have done things differently.
"The reality is this - if Joe had punched [her son] ... as he'd done to her, then [her son's] life could have ended in front of her, while she stood and watched, and did nothing.
"The decision that Karen made in that split second, was not to take that risk - the decision was instinctive.
"She put herself between her son and her partner and she stabbed him twice.
"No particular thought was given to where the wounds were placed... she just did it, Joseph fell to the floor."
Cassidy said if the jury accepted that, it was their duty to find her not guilty of murder or manslaughter.
He said she was "entitled" to protect herself and her boy.
"Once the safety of her son was secure, Karen was quite obviously confronted by the fallout of what she did.
"It was not premeditated."
Cassidy said if the jury accepted the expert evidence, then Ruddelle was "a statistical norm".
"Women do it all the time - it's all they can do," he said.
"Her experience is so similar to so many others ... and it has to stop, for everyone's sake."
He said Ruddelle, after killing the love of her life, "must have fallen to the depths of hell".
"Because that's not what she intended," he said.
Cassidy ended by imploring the jury to use common sense.
"The Crown cannot prove its case beyond a reasonable doubt," he said.
"The defence do not have to prove anything … but in a case as unusual as this, the evidence of self defence and of defence of another is overwhelming."
Justice Palmer will sum up the case for the jury at 10am tomorrow, then send them to deliberate.
