The patrol says 66-year-old Donal Nier of Plainfield had a blood-alcohol level of .19%, more than twice the legal limit.
Nier died in the crash on Jan. 15, as did a couple from Merrill, Robert and Nancy Pfotenhauer.
Nier was traveling southbound in the northbound lane of divided Highway 51. Several motorists narrowly escaped being struck by Nier's truck.
Captain Jeff Frenette said Nier began traveling in the wrong lane after getting gasoline at a convenience store near Merrill, about 13 miles before the crash.