Fifty-one-year-old Martin Williams also pleaded guilty Monday to abandonment of a corpse in the death of 35-year-old Tangela Ann Fisher of St. Joseph.
Her body was found on a rural Platte County road in mid-September.
Williams told the court Fisher died after overdosing on meth. He and 31-year-old Juan Naranjo stashed her body for two days before dumping it.
Williams will be sentenced in February.
Naranjo pleaded guilty last week to hindering prosecution of a felony and possession of a controlled substance. He also is being held for illegally entering the country and is likely to be deported.