BOISE -- The Ada County Sheriff's Office says a man pulled over for erratic driving Sunday was in a van belonging to a missing man from Illinois.

Around 9 a.m. on westbound Interstate 84 east of Eisenman Road, a deputy says he saw a blue Plymouth van going about 60 mph back and forth between lanes, cutting off a semi truck, and nearly causing a crash.

The driver, 25-year-old Jeffrey Maynard, had active arrest warrants from Texas, including charges of theft and attempted arson.

Deputies quickly determined the van he was driving was registered to 62-year-old John Henry Cumby Jr. who had been reported missing from his Illinois home for over a month.

Officials say all Cumby's belongings were found inside the van including his wallet, identification, and other personal items.

Maynard couldn't explain where Cumby was or why he was driving the missing man's vehicle.

The deputy says when he asked Maynard to get out of the van, he grabbed a can of mace from between his legs but dropped it when the deputy noticed what was happening.

Maynard was then arrested and is being held in the Ada County Jail on a $500,000 bond on several charges, including providing false information to law enforcement and assault and battery of a law enforcement officer in connection with his arrest Sunday.

Officials say before Cumby left his Rock Falls, Illinois home in mid-August, he told his family members he was going camping near Denver but would be back by early September. Family members say they haven't heard from Cumby since Aug. 20.

Investigators are still trying to determine where and how Maynard and Cumby met and are concerned about the possibility of foul play.

Investigators are working closely with law enforcement in Colorado and Illinois on the case.