A motorist with a history of drunken driving and who was high on a cocktail of illicit drugs when he fatally struck a man walking on a Duluth sidewalk was sentenced Monday to four years in prison.

David Andrew Smithson, 27, of Duluth, pleaded guilty this summer to driving under the influence of a controlled substance after his minivan struck and killed 37-year-old Brian Respler on Dec. 19.

With credit for time served in jail since his arrest, Smithson will spend a little more than two years in prison and serve the remainder of his term on supervised release. Smithson also was ordered to pay $7,500 in restitution for Respler’s funeral expenses.

Respler was walking about a half-mile from his home on a sidewalk in the 6200 block of Grand Avenue about 4:15 p.m. that day when Smithson’s vehicle left the road near Main Street and struck Respler. Respler was dead at the scene.

In his guilty plea, Smithson said that he had been awake a couple of days and that he fell asleep at the wheel because of his drug problem. He acknowledged using heroin that day.

Tests conducted by the state Bureau of Criminal Apprehension crime lab revealed that the defendant had morphine, amphetamine, methamphetamine and tetrahydrocannabinol (THC), the active ingredient in marijuana, in his system at the time of the crash.

Smithson has two drunken-driving convictions on his record in Minnesota, along with two convictions for drug possession.

Respler moved from New York to Duluth in 2003, overcame a learning disorder and had worked for Goodwill Industries for 10 years at the time of his death, the charity said in an online article ­written in 2014.

“I love it here, because I’m working in an area now which is something I’ve always wanted to do, which is on the docks and the trucks,” Respler was quoted in the article as saying.

Respler’s survivors include a wife and four children.