A man in Migori County allegedly killed his sister-in law on Saturday evening following an argument over claims that his wife had been cheating.
Relatives of the victim, 47-year-old Gati Weisero, said the suspect, Getangata Maroa, had accused her of covering up for his wife.
The family members claimed the man had also threatened to kill Ms Weisero if she did not reveal the whereabouts of his wife, who allegedly eloped with another man.
Mr Maroa reportedly waylaid Ms Weisero as she returned from a well at Girigiri village in Ntimaru Sub-county.
Residents heard the victim's cries and rushed to the scene but it was too late.
Mr Mwita Chacha, a relative, said, "The man had accused the woman of knowing the ways of his cheating wife, something she denied. He then threatened to kill her after the wife disappeared."
Mr Mwita Wanjacho, Ms Weisero's husband, said, "I don't know why my own brother would do this to my wife... I don't know. It's so painful."
The man will now care alone for their six children.
Residents accused police of sleeping on their jobs but asked them to bring the suspect to book.
"We demand that this man be arrested immediately for this heinous act," said Mr Joseph Kerario.
"Most of the perpetrators of such crimes are never arrested. This is why some people find it easy to kill. They know that eventually, nothing will be done to them."
Kuria East divisional police commander Ahmed Abdikadir said the suspect fled immediately after committing the crime.
"The man had issues with his wife and accused the deceased of knowing the secret affair of the wife. He murdered the woman and disappeared immediately after committing the act," said Mr Abdikadir.
The OCPD said police were searching for the suspect who is believed to have gone to neighbouring Tanzania.
"We shall catch up with him and subject him to the law," he said.
Police and local authorities decried rising cases of murder in the area.
A stone's throw away from the scene of the incident, a man killed his pregnant wife using a spear after accusing her of infidelity.
Mr Pintu Boroi Mwita, 24, is said to have quarrelled with Rael Boke Mwita about the paternity of the unborn child. The suspect is still at large.
Police appealed to residents to solve their disputes amicably.
They took the body to Migori County Referral Hospital mortuary.