Diego Novella was convicted for murdering Gabriela Kabrins Alban. Picture: Cindy Waxa/African News Agency (ANA)

Cape Town - The sister of Diego Novella, a Guatemalan convicted of murdering his American marketing executive girlfriend, testified in mitigation of sentence at the Western Cape High Court on Tuesday.

Priscilla Dougherty described her brother, one of seven siblings, as a teenager who was "always full of energy, always happy, always smiling".

But, that all changed in 1989 when his 23-year-old brother Paul died in a tragic car accident. Diego was 15 at the time.

Dougherty struggled to hold back tears as she told the court her brother was declared brain dead but was kept alive for two days so that Diego and her twin brother Lucas could return from boarding school in the United States to say goodbye. 

"I think part of Diego died with Paul. My whole family died after that. My whole family was never the same. We were all shocked, especially effected were Diego and Lucas. Paul was always aware of them and looking after them."

Novella, 45, has been found guilty of murdering Gabriela Kabrins Alban, 39, in the hotel room they were sharing at the Camps Bay Retreat boutique hotel in 2015. She was strangled and suffered blunt force trauma, her body defiled and brutalised. 

The news of the murder reached the family in Guatemala the following day on July 30, when Dougherty received a call from a woman in South Africa. 

"I cannot describe what went through my head, she said it so abruptly, it took me a few minutes. I called my older brother's house. His son answered. I drove there to go to him. We got all the family together and informed the other siblings. I then went into shock. I think I'm still in shock". 

Novella kept his eyes closed throughout his sister's testimony.

During his trial, he argued diminished capacity as a result of psychoactive effects of substances he had ingested that included scletium and cannabis oil and claimed that he thought Alban was a "demonic entity". 

But Judge Vincent Saldanha rejected this in his June judgment and said Novella had been able to distinguish between right and wrong.

African News Agency/ANA