Some notices of driving offenses languished in an electronic queue that no one was responsible for checking. Others — tens of thousands of violation notices sent by mail — were sorted into bins and left in a records room. Yet another set of notices seemed to have disappeared entirely.

After a devastating crash last month in which a pickup truck collided with a group of motorcyclists on a rural New Hampshire highway, killing seven of them, questions have emerged about why the driver of the truck still had a commercial license from the state of Massachusetts even though he had been charged about a month earlier with driving under the influence.

When the driver, Volodymyr Zhukovskyy, 23, was arrested in May, he had refused to be tested for alcohol, the authorities said, which should have disqualified him from operating a commercial motor vehicle for at least a year.

On Monday, Massachusetts officials acknowledged major lapses at the state’s Registry of Motor Vehicles that had allowed not only Mr. Zhukovskyy, but also hundreds of other drivers, to slip through the cracks when they should have had their licenses suspended. In the past three days, registry employees going through old records have suspended the licenses of 546 people, according to the state Department of Transportation, and the search of records is continuing.