Forty state troopers — dressed in plainclothes and riding alongside Chicago Police officers in unmarked Chicago Police Department vehicles — will start serving fugitive warrants Thursday, under a partnership that could last for 60 days, twice as long as originally planned.

The troopers will be assigned to overlapping, ten-hour shifts — starting at 7 a.m. and 3 p.m. — in four high crime Chicago Police districts: Englewood, Austin, Calumet and Gresham.

Sources said the troopers will be housed in an undisclosed suburban motel during a 30-day deployment that could double if the partnership succeeds in getting known criminals off the street.

The Chicago Police Department’s fugitive apprehension unit currently includes 77 officers. The temporary infusion of state troopers will bolster those numbers by 52 percent.

There’s one woman among the 40 state troopers, who will use CPD radios and be drawn from districts across the state to avoid draining any one area at a time when manpower is woefully short.

Final details of the partnership were hammered out Wednesday during a de-briefing at the Harrison Police District, 3151 W. Harrison.

State Police Director Hiram Grau, a former Chicago deputy police superintendent, and his chief of operations Michael Zerbonia attended the meeting. Zerbonia is a brigadier general in the Illinois National Guard with more than 30 years of military expertise, including service in Iraq and Afghanistan.

“The target is fugitive apprehension. But if there’s a crime in progress, they’ll respond with Chicago Police. One thing leads to another,” said a source familiar with the mission.

“That’s why the term `patrol’ is being used loosely. It’s not a beat car. But, they’re still going to be in these [high-crime] neighborhoods. The focus is on providing a law enforcement presence.”

Last week, Mayor Rahm Emanuel emerged from an anti-violence meeting at Kennedy-King College to announce that he had accepted Gov. Pat Quinn’s offer to free up 40 state troopers over the next 30 days to serve fugitive warrants in Chicago.

Hours later, the governor’s office acknowledged that a deal had been cut to create as many as 25 “surge teams” —  each including five Chicago Police officers and two state troopers — to focus on apprehending those with “known violent criminal histories who are wanted by law enforcement.”

Earlier this week, police union leaders urged the mayor to modify the plan.

Dean Angelo, president of Fraternal Order of Police Lodge 7 representing Chicago Police Officers, and Mike Powell, president  of the FOP’s Illinois Trooper Lodge No. 41, said it made more sense to assign state troopers to traffic duty to free Chicago Police officers for the job of chasing fugitives because they know the criminals they’re chasing and are more familiar with Chicago neighborhoods.

Both men called the partnership a Band-Aid approach to a shortage of police officers at both ends. Emanuel balanced his first budget by elimination more than 1,400 police vacancies.

“I don’t why we’re taking people completely out of their element and supplementing the lack of manpower in Chicago,” Angelo said then.

“It’s a nice, temporary fix that will assist our daily activity without fixing anything. The focus has got to be on the need for more police officers. We can’t lose sight of that. “

Powell stressed that state troopers are fully capable of handling whatever assignment they’re given and, “We feel an absolute obligation to help out Chicago Police.”

But, he also said, “We are under-staffed by anywhere from 600 troopers to 1,000.”

Police Supt. Garry McCarthy did not attend Wednesday’s final meeting at the Harrison District. But, he has argued that fugitive apprehension is the “simplest way to reduce crime” on the streets of Chicago.

“They’re wanted today. You put handcuffs on them, they don’t commit a crime tomorrow or later on today,” McCarthy told reporters earlier this month.

“When the mayor and the governor were having conversations about, what could they do, I very simply said, ‘Get us some folks to work fugitive apprehension with us.’ Our fugitive team [was] expanded a couple of years ago. We think we have it right-sized. But more means we can go out and arrest more wanted people, which is obviously going to help us.”