Michael Gagnon pleaded no contest to five counts of aggravated vehicular homicide and two counts of aggravated vehicular assault. A Lucas County, Ohio, judge found him guilty.
Police said his blood-alcohol level was more than double the legal limit, and assistant prosecutor Jeff Lingo said yesterday that tests also showed Gagnon had marijuana in his system.
Gagnon faces up to 50 years in prison and is to be sentenced June 27.
Bethany Griffin, 36, of Parkville and three of her daughters - Vadi Griffin, 2 months; Lacie Burkman, 7; and Haley Burkman, 10 - died in the crash along with Jordan Griffin, 10, the daughter of Bethany Griffin's husband, Danny Griffin Jr., 36.
Danny Griffin was injured in the accident along with 8-year-old Sydney Griffin.
As Gagnon walked through the courtroom yesterday with his hands cuffed and feet shackled, family members of the victims, including Danny Griffin, grew quiet. When it was over, they left the courtroom without speaking to reporters.
Griffin sat quietly during the hearing, holding a necklace he was wearing against his lips.
Gagnon stared blankly ahead while Lingo went over what happened the night of the crash.
"He knows how serious it is," said his attorney Richard Sanders. "He realizes the devastation it caused."
Authorities said Gagnon had been drinking with family at a bar on Dec. 30 to celebrate the New Year when he went out for fast food and took a wrong turn onto Interstate 280 in Toledo.
He had ordered five buckets of beer and 10 shots of tequila that night, Lingo said.
Gagnon drove about four miles in the wrong direction and just missed several other cars before his truck struck the minivan filled with six children and a husband and wife who had spent Christmas with their family in Michigan, authorities said.
At the crash scene, Gagnon told a witness, "I'm wasted," Lingo said. His speech was slurred and he smelled of alcohol at the crash scene, police said.
After the accident, Gagnon's family members said that he made a mistake but that what happened was out of character for Gagnon, who had been attending community college to become an architect.
He and his brother owned a construction business.