The jury selection could last several days and the trial could last through most of October.
Rafferty, who is being tried as an adult, and his co-defendant, Richard Beasley, 53, of Akron, have pleaded not guilty. Beasley will be tried separately.
Rafferty, who was then 16, is suspected of helping Beasley lure victims with bogus job offers.
Three men were killed last year — two in Noble County in southeast Ohio and one found slain in Summit County near an Akron shopping mall — after responding to what authorities said were bogus online job postings.
Rafferty cannot face execution because he was a juvenile at the time of the crimes. Instead, he could face life in prison.
Prosecutors are seeking the death penalty against Beasley.
The body of David Pauley, 51, of Norfolk, Va., was found on Noble County property owned by a coal company and often leased to hunters.
Timothy Kern, 47, of Massillon, was found in a shallow grave near an Akron-area shopping mall. He had been shot in the head.
The body of Ralph Geiger, 55, of Akron, was found in Noble County and had died Aug. 9 of a gunshot wound to the head.
A South Carolina man, Scott Davis, escaped after being shot in the arm by hiding in woods until it got dark. He has been subpoenaed to testify at Rafferty's trial.
Beasley was a Texas parolee who returned to Ohio in 2004 after serving time on a burglary conviction. He was awaiting trial on prostitution and drug charges when authorities took him into custody.
Police have said a halfway house he ran in Akron was a front for prostitution. Authorities said he was a mentor for Rafferty and had befriended him.