The sister of Pelin Kaya has described her killer as a "devil" who deserves to spend the rest of his life behind bars. 

Jeremy Camilleri, 34, pleaded guilty on Monday to the murder of the 30-year-old interior designer.

She was mowed down by his BMW car as she walked home along Testaferrata Street, Gżira from a birthday celebration on January 18 last year. 

Derya Kaya said she felt no sense of relief after Camillieri changed his plea to guilty after initially denying the murder charge.

She said the family had been prepared "to fight in any way" because they already knew that he was a murderer. He had initially tried to overshadow the "barbaric murder" by claiming he needed psychiatric tests, she said.

“Now everyone knows what we know, he is a murderer, he is a devil, and his every move and every step is deliberate, he is a devil and deserves life imprisonment,” she told Times of Malta. 

"I am aware that no one wants to protect him. I hope justice will be served and they will sentence the devil to prison until he dies."

Pelin Kaya (left) and her sister Derya Kaya. Photo: Derya Kaya

Camilleri will be sentenced for the murder at a later date after the case is assigned to a judge.

Earlier, their family lawyer Shazoo Ghaznavi told awaiting media that the guilty plea would at least spare the family the pain of having to travel from Turkey for court hearings. 

"Nothing will take the pain away. This will not bring their daughter back," he said.  

In an interview with Times of Malta last month on the anniversary of the murder, Derya Kaya said she had "absolute faith" in the Maltese justice system and that Camilleri would be punished in the "harshest" manner. 

She described her sister as the "jewel of the family".

Camilleri, 34, was arrested in Gżira shortly after he mowed down Kaya and smashed his BMW into a fuel station and KFC restaurant just after 2am. 

He later told the police that he “wanted to be famous” and that he was “a psychopath and proud”.