The perpetrators at one point took the captives round the village where they had been spotted during the day, trying to force a confession out of them.
Passers-by rescued Mr Muchangi while the lifeless body of Mr Gichovi was spotted dumped a few metres from where they were beaten up.
The body had cuts and bruises.
Mr Etyang said members of the public had volunteered information, leading to the arrest of the woman but her accomplices fled.
The body was taken to Embu Level 5 Hospital mortuary.