The body of an 11-year-old girl was found at Moi's Bridge Railway Station on Wednesday morning.
Mr Fanuel Nasio, Soy Sub-County divisional police commander (OCPD), said it was suspected the girl was defiled and then strangled.
“She had been sent by her mother to buy supper in Moi's Bridge town at 6 pm on Tuesday but did not return home," Mr Nasio said.
“We have started a thorough investigation to determine what happened and to arrest those involved in the heinous act,” he told journalists at Moi's Bridge Police Station on Thursday.
Mr Nasio said no suspect had been arrested so far but they were following a lead.
He told parents not to send children on errands when it is late.