CAMBRIDGE, Mass. (AP) — Robert Parker, the author of the popular "Spenser" novels about a hard-nosed Boston private investigator, has died. He was 77.

A spokeswoman for the Cambridge police department says an ambulance was sent to Parker's home at about 11 a.m. Monday for reports of a sudden death. The spokeswoman, Alexa Manocchio, says the death was of "natural causes" and is not considered suspicious.

A publicist for Parker's publisher confirmed the death but had no further details.

Parker wrote more than 50 novels, including 37 featuring Spenser. The character was the basis for the 1980s TV series "Spenser: For Hire," starring Robert Urich.