A Manhattan man serving 20 to life for murdering his common-law wife has confessed to also killing his first common-law wife, admitting that he cut off her head and buried it in Riverside Park, prosecutors said yesterday.

Philip Ward, 45, had long been a suspect in the 1989 murder of the pregnant Veronica Bowen but was never charged with the crime until yesterday.

“After 18 years of being in prison for killing his second wife, what motivated him to confess now I don’t know,” said Ward’s lawyer, Frank Rothman, but he is hoping the move will help him to have “some sort of relationship with his children.”