PHOENIX -- The red Bombardier all-terrain vehicle that missing person Mark Russell Irby was last seen riding has been located, said the Coconino County Sheriff.

Reports say two men from Snowflake who were hunting and fishing in the area late Saturday found the abandoned ATV just off Forest Service Road, about 12 miles from Irby's home in Forest Lakes.

On Sunday, 11 deputies, officers and volunteers from Coconino County searched the area. Intensive search efforts will continue this week.

Reports say Irby had planned for a short ride the morning he disappeared on January 2, 2009. He was last seen wearing a denim shirt, blue jeans and "Croc" style plastic shoes and was not prepared to hike or stay overnight in the area.

Prior to the location of his ATV, several agencies have searched for Irby for over 1,800 hours by land, eight hours by helicopter, and 20 hours by plane.

A criminal probe has been opened in relation to his disappearance.