Riley died at the hospital after suffering stab wounds to his torso.
Riley is an Ohio native nicknamed "the Incense Man" due to his practice of selling aromatic burning sticks at local farmers markets. He was considered a peaceful and friendly fixture on the streets of his adopted coastal hometown, according to area residents and merchants.
Aided by surveillance camera footage, SDPD investigators identified Jackson as the suspect in the case. Police did not say what other evidence led them to Jackson.
Jackson was booked into San Diego County Jail on suspicion of murder.