Officials said Saturday that they are seeking a Mexican identified as Jesus Gastelum. Police Sgt. Tom Wagner says he is believed to be in Las Vegas or Southern California.
Police also have someone else in custody, but they did not identify that person.
Those two are in addition the boy's grandfather. Clemons Tinnemeyer was arrested Friday in Southern California. Police think he was involved with Mexican drug dealers who wanted to send a "message" with the abduction.
Police say they continue to search for the boy and are focusing on the northeastern Las Vegas Valley.
Authorities called off an Amber Alert in their search for Cole Puffinburger earlier Saturday. Las Vegas Police Capt. Vincent Cannito said the "effectiveness of the Amber Alert has run its course," and tips had slowed considerably.
But Cannito said alert's cancellation "does not minimize the efforts being put forth by the law enforcement community." He also said the widespread media coverage of the kidnapping would serve the same purpose as an official alert.
Cannito said that authorities had executed a number of search warrants around the country that have yielded more leads, including the recovery of large amounts of cash.
Tinnemeyer was arrested late Friday in the city of Riverside by a fugitive task force, FBI spokesman Joseph Dickey said. He was being held at the Central Detention Center in the city of San Bernardino.
Tinnemeyer, 51, may have stolen millions of dollars from the Mexican nationals, said Officer Cris Johnson, a Las Vegas police spokesman. Johnson declined to say what role Tinnemeyer played in the drug operation or whether the kidnappers were seeking a ransom.
Police believe methamphetamine was involved, Johnson said. Two men entered Puffinburger's home Wednesday and tied up the boy's mother and her boyfriend. The home was ransacked and the boy abducted.