An elderly murder suspect took his own life days after the body of a teen girl was mysteriously found in a senior community.

Kyelonna Meya Smiley, 15, was discovered in the apartment near 75th Avenue and Encanto Boulevard in Phoenix at 9.40am on August 4.

She had been fatally shot in the head and Nohe Prado Morelia, 67, was quickly linked to the crime - though police won't say how.

Four days later, Morelia was found dead with a self-inflicted gunshot wound at a business near 24th and Van Buren streets.

Phoenix police said they were satisfied Morelia murdered Kyelonna, but without any idea of a motive they closed the case.