A couple, detained in Mexico while transporting human body parts in a baby carriage, has admitted to killing 20 people, twice the number originally suspected.

Under interrogation, the man, identified as "Juan Carlos N", confessed on Monday to raping and murdering 20 women, and selling their body parts and belongings, Alejandro Gomez, the chief investigator on the case, said.

Carlos and his wife, "Patricia N" - their last names withheld in accordance with Mexican laws - were arrested on Thursday in Ecatepec, a violence-hit suburb northeast of Mexico City, on suspicion of killing 10 women.

Single mothers

Outrage in Ecatepec