A jilted man attacked the family of his former girlfriend, killing her brother and seriously injuring the mother, a court has been told.

High Court judge Justice Thrispisa Cherere heard that Evans Otieno alias ‘Designer’, stabbed Brian Ochieng' to death and seriously injured his mother Salome Atieno last December 27.

The mother was stabbed in the back in an attack that also saw the accused allegedly try to burn his former lover's family house.

Lavender Akinyi, the accused's former girlfriend, said Otieno had been harassing and intimidating the family for a long time.

“He would come to my bedroom window, smoke bhang and exhale all the smoke towards me. There is a time he threw a burning matchstick on my mosquito net at night," said Akinyi.

"Another time he threw his phone into my room through the window and started demanding for it,” Akinyi added.

The 22-year-old testified that her former boyfriend went to her home several times, mostly at night, to intimidate her family. Her brother, Ochieng', had warned him against the intimidation.

“There is a time he confronted my brother when I was returning a borrowed jerrycan to a neighbour. We saw a knife attached to his belt. Fortunately, Brian (Ochieng') snatched the knife and threw it away before he could use it,” she said.

Akinyi then decided to go to Nairobi, hoping her absence would make the accused to stop visiting her home.

Fenny Achieng, 16, the deceased’s younger sister, said she saw Otieno attack her mother and brother.

“Brian and I were bringing mum some drinking water when we saw the accused pull out the knife. In an attempt to defend mother, Brian got stabbed in the stomach,” she said.

She said Ochieng' ran after Otieno but fell down, as he was bleeding heavily.