Updated 12.30pm - Added timeline

Former drama teacher Erin Tanti on Friday pleaded guilty to charges he murdered 15-year-old Lisa Maria Zahra at Dingli Cliffs in 2014 and was handed a 20-year prison sentence.

Mr Tanti had been accused of wilful homicide as well as with having assisted his teenage student in committing suicide, after the two had allegedly been discovered at the bottom of the cliffs on March 19, 2014.

The man was also accused of having defiled the underage girl at the time when he was her teacher.

Mr Tanti admitted to committing all the charges against him.

His trial by jury was due to start on Friday but as the case was about to begin and before the jury had been empanelled, he filed a last-minute admission to receive a mitigation in punishment.

Judge Consuelo Scerri Herrera, presiding over the case, handed down a 20-year six-month sentence.

Tony Zahra, the father of the victim, hurled abuse at the accused as the sentence was read out.

Lawyers Michael and Lucio Sciriha served as defence counsel.

In comments after Mr Tanti’s guilty plea, the victim's cousin, Winston Zahra, speaking on behalf of the family, said that the past five years have been extremely difficult for all the family, who had to come to terms with the death.

“Apart from the trauma of what happened, the long drawn-out legal process and the fact that as a family we could not publicly discuss the case to correct the misconceptions reported by some of the media, despite having seen all the clear evidence that Lisa Maria was murdered, made matters more difficult," he said.

The victim's family with lawyers outside court. Photo: Matthew Mirabelli

“Today we can finally speak out. By Mr Tanti’s own admission in court this morning, on March 19, 2014 Lisa Maria Zahra was murdered by the very person who had a duty of care to look after her. Erin Tanti was an adult. He was Lisa Maria’s drama teacher. Lisa Maria was his 15-year-old student who would still be alive today were it not for this man.

“We have always known as a family that this was a case of murder and finally after a long drawn out five years Erin Tanti has admitted in court to the crime of murdering Lisa Maria,” Mr Zahra said.

Speaking about the foundation set up in his cousin’s name, the Lisa Maria Foundation, Mr Zahra said the foundation will continue to work hard in her name to do “whatever possible to help safeguard our children” and continue to ensure that there are the necessary checks and balances in place when people are employed and entrusted with the care of children.