Police in Kirinyaga are looking for a 31-year-old man accused of killing his elder brother after discovering they were both having an affair with their 17-year-old step-sister.

The incident happened on Saturday, December 3 in Chema Village, Ndia Constituency.

According to the Directorate of Criminal Investigations (DCI), the suspect killed his brother at their home after busting the elder sibling in a compromising situation with the teenage girl.

"A fight broke out between the suspect and the deceased," said the DCI in a statement on Twitter.

The 37-year-old brother died of his physical injuries, police said.

According to authorities, the victim died of blunt force trauma to the head. He'd also been assaulted in the face and back.

The 37-year-old man's body was moved to the Karatina Sub-County Hospital morgue.

The DCI said the now-deceased had, in March 2022, impregnated their 17-year-old step-sister, whose unborn baby died in the womb.

The brothers shared a biological father with the girl, but had different mothers.