LAS VEGAS (AP) -- Authorities in Southern California arrested the grandfather of an abducted 6-year-old Las Vegas boy, saying they believe that the man was involved with Mexican drug dealers and that the kidnapping was a "message."

Clemons Tinnemeyer was arrested late Friday in Riverside on a federal material witness warrant. He was being held in San Bernardino, and authorities hope his arrest will help lead them to Cole Puffinburger's abductors.

Authorities had issued an Amber Alert that triggered a public search for the boy and flashed his photograph on billboards and highway signs throughout Nevada and California.

The alert was called off Saturday, but authorities said the search for the boy continued. They gave no details on why the alert was canceled but planned an afternoon news conference in Las Vegas.

Cole was abducted from a Las Vegas home Wednesday morning by two men posing as police officers. Police said they believe that the men were Mexican drug dealers and that the kidnapping at gunpoint was a "message" to Tinnemeyer, 51.

The two men entered the home and tied up the boy's mother and her boyfriend. The home was then ransacked and the boy abducted.

Las Vegas police Capt. Vincent Cannito said that a third man was believed to be involved and that police had several other persons of interest but no suspects in the abduction.

Tinnemeyer may have stolen millions of dollars from the Mexican citizens, 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.

Authorities also were investigating whether other family members had ties to the drug operation, Johnson said.

"Money is a huge factor, obviously. Drugs are a huge factor," Johnson said. "The only innocent person involved in this entire operation is the boy."

Court records show Tinnemeyer and his wife filed for Chapter 13 bankruptcy in 2001, claiming $226,500 in assets and $329,000 in liabilities. The couple listed more than $15,000 in credit card debt.

(Copyright 2008 by The Associated Press. All Rights Reserved.)