A teacher accused of encouraging his 15-year-old girlfriend to commit suicide purchased almost 100 aspirin tablets from a pharmacy the day before her death.

Erin Tanti, 24, bought three boxes of medicine from a Valletta pharmacy on the eve of Lisa Maria Zahra’s death, the same day that her brother, Nicky, filed a police report that Mr Tanti had slept with his sister at their house.

Mr Zahra testified that he was “shocked” when he Googled Mr Tanti’s name. He said the name of a play he was producing came up first but he preferred not to say what its title was.

“I saw that, like my sister, he was involved in Masquerade. I saw an advert of a play and I got worried. I sensed there was something wrong so I sent an e-mail to my father about the matter since he was abroad,” he said.

It was the first time she remained at the house while her father was away because his sister would stay with her grandmother, he said. Mr Zahra said he had no idea of the relationship and could not understand what a man who at the time was 23 would be doing with a 15-year-old.

Mr Tanti is being accused of the girl’s murder, assisting her to commit suicide, defiling her, being in possession of indecent images of the teenager and abusing his position of trust as her drama teacher.

Mr Tanti, who is pleading not guilty to the charges, appeared in court accompanied by his father, who attends every sitting, and a nurse. Ms Zahra was found dead at the foot of Dingli Cliffs on March 19. Mr Tanti was found a few metres away, slightly injured but lucid. He told police officers the two had fallen from the cliff.

Her brother, 21 years her senior, admitted he was not that close to his sister, although they met over the weekends.

He knew there was a problem with self-harming because his sister cut her arms and thighs with a blade and had spoken to her about it. However, he did not get much out of her because she was “evasive”.

“There were superficial cuts on her arms and thighs. I asked her several times whether something was bothering her but she was evasive. I thought it was part of the rebellion stage,” he said.

He testified that the night before she was found dead, she sneaked out of home unnoticed and, in the morning, when he could not find her anywhere, he filed a missing person report and the police began investigations.

Ms Zahra’s cousin, Tania Mercieca, said the school had drawn their attention to the self-harm issue and they had taken her to psychiatrist Ethel Felice who referred her to a psychologist.

The case continues.

Police Inspectors Keith Arnaud, Sylvana Briffa and Josric Mifsud are prosecuting.

Lawyers Michael and Lucio Sciriha appeared for the defence.

Lawyers Giannella de Marco and Joseph Giglio are representing the Zahra family.