“Self-obsessed” Taye Francis already had convictions for rape and violence when he killed 23-year-old Khloemae Loy in a hotel room last July.
The steroid addict sent a picture of Ms Loy lying dead on a bed to his lawyer saying “I’ve killed my girlfriend” as he called 999, jurors heard.
Ms Loy was pronounced dead at the scene in Greenwich, south-east London.
Prosecutor Kate Lumsdon QC had told jurors there was no issue that Francis killed her, but they must consider whether he was suffering from any mental condition at the time.
She said: “Mr Francis was a violent, self-obsessed man who took steroids.
“Apart from building muscle mass, steroids have various side effects. These include aggression and paranoia.
“Our case is that he killed her in anger. It was murder.”
Francis, 40, of no fixed address, who had admitted manslaughter by diminished responsibility, was found guilty of murder by a majority of 10 to two on Wednesday.
He was remanded in custody to be sentenced on December 6.
The court heard how Francis, formerly known as Ashley Wyatt, had a string of convictions for violence against women.
In 2002 he was jailed for six years and placed on the sex offenders’ register for two rapes, kidnap and having a blade.
In 2013 he was handed a non-molestation order and jailed for assaulting another woman who he threatened to kill and stab in the neck.
Two years later, he was convicted of criminal damage during a domestic incident.
In 2016, he was given a conditional discharge for attacking an ex-girlfriend.
Ms Loy had met the defendant while working at a pub near Croydon College, where she was a student.
She told her parents, Maxine and Dany Loy, that he was 26 when he was in fact much older, and also, wrongly, that he was a fellow student.
In 2017 Francis assaulted Ms Loy and threw her in a wheelie bin, jurors were told.
He was convicted and given a 20-week sentence with a restraining order.
Ms Lumsdon told jurors: “Her parents encouraged Khloemae to leave Mr Francis.
“Khloemae said she could not leave him or he would attack Mr and Mrs Loy.
“The records paint a picture, you may think, of an aggressive, controlling man and a troubled, frightened woman who is struggling with her mental health.”
The day before the murder Ms Loy cancelled a shopping trip with her mother, saying she was going to the coast to meet her boyfriend’s parents.
On July 5 last year Ms Loy was found lying on a bed at a hotel in Greenwich with a deep cut to her neck.
Francis was hanging from a ledge outside, having thrown a small rucksack and a suitcase out of the window.
The defendant, who had cuts to his body and had recently taken steroids, was eventually dealt with by the emergency services, put into an induced coma and taken to hospital.
When uniformed police knocked on the door of the victim’s parents’ door, Mr Loy answered and said: “He’s killed her, hasn’t he?”
In an impact statement, her parents said: “Khloemae was only 23 at the time of her death. She is missed by her family and friends. We all miss her bubbly personality, she was always the life and soul of the party and she always tried to see the best in everyone. She was like our little china doll.
“At the age of 23 Khloemae had already endured five years of suffering at the hands of Taye Francis when all she did was seek love and commitment from him.
“Taye tricked her into his world. He lied to her from the very beginning. He lied about his age, his job and the fact he was a student at a local college, He tried to manipulate and control Khloemae from the outset. He took her away from her family and friends and physically and emotionally abused her.
“Even though Khloemae is no longer here with us she still exists. Taye has taken Khloemae’s life but in doing so he has also ruined ours. We cannot experience her love and happiness.”
Emma Currie, from the CPS, said: “Taye Francis was not only controlling, violent and angry – he was also utterly paranoid and walked around wearing a stab vest. As a registered sex offender, he was convinced everyone knew about this and was out to get him.
“Khloemae Loy was an innocent victim in this and tragically lost her life after being caught in a spiral of abuse at the hands of Francis.
“The prosecution was able to present strong witness testimony from toxicology experts and a history of evidence detailing previous abusive incidents relating to Francis’ former partners as well as Khloemae.
“The defence argued that Francis had suffered with a medical illness impairing his thinking and resulting actions, but the prosecution was able to prove to the jury that in fact Francis had become paranoid as a result of voluntarily taking anabolic steroids.
“Domestic violence can have a devastating impact. The CPS is dedicated to bringing offenders to justice wherever possible. Although nothing can bring Ms Loy back, I hope this conviction provides some sense of justice for her family and friends. Our thoughts remain with them at this time.”
Detective Sergeant Quinn Cutler, from the Metropolitan Police, said: “Taye Francis is a violent, controlling man who subjected Khloemae to constant aggression and abuse as a result of his own paranoia.
“His horrific actions have robbed a family of a much-loved young woman who had her whole life ahead of her and our team were determined to get justice for her and those left bereft by her loss.
“Domestic abuse should never be tolerated and across the Met we are working hard to protect women and girls across the capital. We want anyone who is subject to abusive or controlling behaviour to know we are here for them and we will listen. If you need us, contact 101 or 999 where we have specially trained officers who can provide support and investigate.”