BIG RAPIDS, Mich. (AP) -- Family members of a Michigan man whose car was found in a remote area of Mark Twain National Forest in southern Missouri are stepping up efforts to find him.

The Holland Sentinel reports Fred Byrne's brother-in-law compiled a list of more than 70 counties between Holland, Mich., and Carter County, Mo., where his car was found. Family members plan to call law enforcement agencies.

The 49-year-old Big Rapids man has been missing since Feb. 12, when he dropped his son at Hope College in Holland and visited his mother.

Byrne's Chevy Malibu was found along a forest service road near Van Buren, Mo., about 160 miles southwest of St. Louis and roughly 560 miles from where he was last seen.

The car might have passed through Indiana and Illinois.