A woman who callously stabbed her partner to death as he ate pizza, leaving a large kitchen knife embedded 23cm deep in his back, has been jailed for life.

Branded "a liar with no moral compass" by Judge Oliver Saxby KC, convicted murderer Nina Mercer, 43, was told today (March 18) she will have to serve a minimum of 17 years before she can apply for parole.

Jurors at Maidstone Crown Court took approximately five hours to reject her case that she had acted in self-defence when she attacked 61-year-old Alan Tomkins, a convicted child sex offender, in his Strood flat.

After friends concerned for the dad of two's welfare had alerted police, officers found him dead on the floor of his hallway on July 26 last year, three days after drug addict Mercer had inflicted the fatal wounds.

She had fled, only to return within an hour of the murder with a friend, Lee Robinson, who shamelessly stole the dead man's wallet and bank card before using it to buy groceries and obtain cash.

Mercer also stopped long enough to wash her hair before leaving the flat for a second time, using the victim's money in the aftermath of his brutal death to also buy drugs and McDonald's.

Mercer, of Gun Lane, Strood, had denied murder but was found guilty on Friday at the end of a four-week trial.

Imposing the mandatory life sentence and minimum term, Judge Saxby told her there was evidence she had not only been physically aggressive to Mr Tomkins in the past, but also to other previous partners, one of whom was said to have been left "a shadow of himself" by her abuse.

Mr Tomkins had himself spoken of being scared of Mercer, that she had "gone for him over money", and would call him a "pervert" if he refused to give her cash.

She had also once threatened to "slit his throat", the court heard.

But Judge Saxby said despite Mr Tomkins being "argumentative, rude and angry in drink", as well as having committed "the gravest of sexual offences", he did not "deserve to be killed".

Of events that evening, he told Mercer: "There is no evidence he attacked you or was about to attack you. His phone had recently called a drug dealer’s number. You were wanting drugs.

"Some sort of argument started – most likely to do with him giving you money. He responded in a way that made you lose your temper and, in anger, you proceeded to attack him with a large kitchen knife, stabbing him in the chest and then, as he tried to get away, in the back and neck.

"As he lay dying, knife embedded in the final wound, you had a choice: See if his life could be saved. Do something to help. At least try. Or else leave him for dead and try and save yourself.

"You chose the latter, putting on a T-shirt over the one you had been wearing and leaving shortly afterwards in search of someone to confide in.

"The court hopes that, at some point in the future, you will find some sort of moral compass – you have none at the moment.

"As and when you do, leaving him for dead is likely to weigh heavily on your conscience."

Robinson, 45, of Frindsbury Road, Strood, was the person Mercer chose to "confide" in and he also stood trial, accused of assisting an offender by disposing of evidence, including her bloodied T-shirt.

Although he was found not guilty by the same jury he had admitted theft and fraud in relation to Mr Tomkins' belongings as well as bank cards and coins stolen from another property around the same time, and was also sentenced today to a total of two years and four months' imprisonment.

The prolific offender, who has more than 80 convictions for dishonesty, was not in court to learn his fate, having refused to leave Sheppey's Elmley Prison.

But appearing over a link he was told by Judge Saxby that he was responsible for the "particularly abhorrent feature" of stealing from the deceased Mr Tomkins.

"You were both in it together – each party to the theft of his wallet as he lay, dead, at the foot of the stairs with a knife embedded in his back and the blood still drying around him," said Judge Saxby.

"The size of the hallway is such that, in passing up and down it – as you will have done on a number of occasions – you will have to have stepped over his body.

"How little had you come to value the life of others, set against your own selfish interests. And to make matters worse, you proceeded to use its contents to buy groceries and then drugs, using his car to do so.

"Neither of you had done anything to help Mr Tomkins as he lay dying nor respect his body as it lay dead.

"To the contrary, you had continued your way of life without pausing for breath, pretending to be surprised when informed of his death and likely murder."

Robinson, the judge continued, then "hit new depths" when he stole from someone who had been kind to him and provided him with a home.

In deciding the appropriate sentence for his offending, Judge Saxby added that although Robinson had made progress while on remand awaiting trial, he had not demonstrated any remorse to the jury.

"Not one word of what you said in evidence demonstrated to me that you have any appreciation of quite how wrong what you did was," he told Robinson.

"Sorry for yourself, and the position you are in? Yes. Sorry in a wider sense for acts which defy decency? Absolutely not."

In a sense of irony, Mercer was in the dock to learn her punishment despite often refusing during the trial to leave her cell at HMP Bronzefield in Surrey.

A letter in which she expressed what her lawyer John FitzGerald said was genuine remorse was read out.

She said: "I am deeply sorry...I have no memory. You can imagine how difficult it is for me that I have actually done this. I can assure you I never, ever would have intended to kill anyone."

However, Judge Saxby said her words were "too little, too late".

At trial, jurors heard she and Mr Tomkins shared a "difficult, mutually violent" relationship, with each at times reporting the other to police.

Although both were habitual drinkers, Mercer also abused heroin and crack cocaine and led a "chaotic" lifestyle.

Mr Tomkins on the other hand not only had his flat but also money from selling at street markets and an inheritance.

Prosecutor Hugh Davies KC said their relationship had "transactional characteristics", with he most likely funding her drug habit and she offering him "a degree of friendship and sex" in return.

She would also give him goods she had shoplifted, sometimes as much as £300 a day.

At the time of Mr Tomkins’ murder, Mercer had just 43p in her account and was awaiting her monthly £700 benefit payment.

The last independent witness believed to have seen the victim alive was a Papa Johns delivery driver when he knocked on his door at around 6pm on July 23.

Less than 20 minutes later he had been fatally stabbed by Mercer in anger.

Part of the pizza he had ordered was later found by police on a plate by an armchair in his front room, along with half a bottle of wine.

Although Mercer chose not to give evidence in court, she claimed through her legal team that Mr Tomkins had been drunk, threatening, and holding a knife that evening.

But Mr Davies told the jury there was "no lawful justification" for Mr Tomkins' being attacked, whatever the reason - and however unattractive his criminal past was.

His multiple stab injuries included the one to his back which penetrated a lung and into his heart, another to his neck, one to his shoulder and defensive wounds to his left hand.

Having fled, leaving Mr Tomkins either bleeding heavily or already dead, Mercer met up with Robinson and they returned, stealing the deceased's wallet, before leaving in his vehicle.

However, Mercer was to go back to the flat several times over the next few days and was arrested on yet another return trip to Newark Court a few hours after her victim's body had been found.

Police bodyworn camera footage showed her asking "Why?" several times and enquiring what had happened as she was detained.

Although it was later accepted at trial that she had inflicted the injuries that killed Mr Tomkins, it was argued she never meant to hurt him and had "blocked out the trauma" of that evening.

She disputed in her letter read at the sentencing hearing that she had been in a relationship with him, and said she did not know the extent of "what he had done" until she read court documents.

Mr FitzGerald said that the fatal stabbing was "spontaneous" and lacked any planning or premeditation.

Although there was no evidence of Mercer having a psychiatric illness, the lawyer said she was "plainly someone who was of a vulnerable mind" and struggling with her mental health.

Referring to her letter, Mr FitzGerald added: "She was absolutely insistent I read that to the court. I ask the court to accept that while she has been found guilty of murder, she is deeply sorry.

"And if it is the case she can't remember, then I ask the court to recognise how difficult it must be for her to deal with the fact she is responsible for his death."

Robinson stole a total of £163 from Mr Tomkins, and £181 from Christopher Brown, who was described in court as a Good Samaritan who had "offered shelter at a time when he was vulnerable".

Tom Dunn, defending, described his client's criminal actions as "ugly but opportunistic", committed in the "grips of a decades-long, merciless addiction" to class A drugs.

"It created a need to self-medicate that was entirely undented by the horrendous circumstances in which this offending occurred," he added.

Judge Saxby rejected assertions that drug addiction was to blame for their actions, telling the pair: "You have both been given support and countless opportunities to address your addictions – support and opportunities which others with more resolve have taken up."

The court was told Mr Tomkins was estranged from his family when he died and no impact statements from his children or brother had been provided for sentencing purposes.