(CBS) — A half-eaten hamburger led authorities to a Chicago man who acted as the getaway driver in a series of bank robberies in western Michigan over the last two years, federal prosecutors said.

Dominick T. Johnson, 34, was sentenced Wednesday to 72 years and eight months in prison for the heists he carried out with his 24-year-old half-brother Nathan Benson, according to the U.S. Department of Justice.

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Prosecutors say Johnson was the brain and the wheels behind the three successful bank robberies that happened between May 2014 and January 2015 in Kalamazoo County, about 150 miles northeast of Chicago.

In two of the robberies, Johnson listened in on a cellphone from a car while Benson forced employees into bank vaults at gunpoint, prosecutors said. Cellphone tower data placed him near the banks at the time of the crime.

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While speeding away from one robbery in Oshtemo Township, Johnson apparently tossed “a partially eaten hamburger” from the vehicle, and investigators were able to pull his DNA from it, prosecutors said.

The duo made three other failed bank robbery attempts, twice thwarted by police and once when Johnson crashed their vehicle on the way to the heist, prosecutors said.

Johnson was convicted in January in U.S. District Court in Grand Rapids of seven crimes, including conspiracy, bank robbery and weapons charges. Benson was found guilty for his role in the robberies and sentenced to 14 years in March.

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