By Pam Zekman

(CBS) — Police sometimes agree to be lenient on criminal charges in exchange for information to solve a crime or get guns off the street.

Are they abusing the tactic?

That’s the allegation in a lawsuit recently filed against a Cook County deputy sheriff and the sheriff’s office.  2 Investigator Pam Zekman reports.

“We need some guns. You come up with some guns or you’re going to jail.”

Jasmin McBride says a Cook County deputy made the threat after allegedly finding crack cocaine in her pocket and learning she was on probation.

The confrontation happened  after Jasmin’s boyfriend was stopped for failing to signal before turning a corner at Marshfield and 69th Street. He did not have a driver’s license. Jasmin was a passenger in the car.

“She told me the police had her and they wanted some guns to release her,” says Patricia Hicks, the mother of Jasmin McBride.

Jasmin spent 13 hours locked up while her mother tried to get the guns requested by Deputy Adam Murphy.

Hicks says she bought one gun from a dealer on the street, for $500.

As instructed, Hicks communicated her progress by texting deputy Murphy on his cell phone. She saved the texts.

In one, Deputy Murphy asked: “You have all three”?

“I was told to get one,” Hicks responded.

“The deal was two for your daughter and one for the car,” Murphy texted back.

“You need those so I can release Jasmin,” Murphy texted.

Hicks did secure a second gun for $500 from the same street dealer and prepared to leave them for the deputy.

“I wrapped them in a black bag and I came down and put them behind the garage can right here,” Hicks says.

Hicks said Deputy Murphy then picked up the guns and released Jasmin.

“He said, ‘Your mom really loved you cause she came up with the guns,’” the daughter recalls.

After releasing Jasmin, Murphy pushed her to turn over the third gun in their “deal,” and her mother hired an attorney, who filed a lawsuit over the tactics.

“Making me go out in the street, talk to people about buying guns, taking my mortgage money to pay for guns, sending me in the middle of the night to knock on doors for guns — how could that be right?” Hicks says.

Her attorney, Jared Kosoglad, says: “The sheriff’s department extorted my clients and held them ransom, unless the family obtained firearms, so that Jasmin could be released.”

Citing Deputy Murphy’s reports, the sheriff’s office denies the scenario presented by Jasmin and her mother.

“It was Jasmin who said, ‘Will you let me go if I find some guns?’, and Jasmin communicated with her mother,” Cook County Sheriff’s spokesperson Cara Smith says.

“I think law enforcement has tremendous discretion in how to handle cases,” Smith says. “With the violence that is plaguing the city, they certainly have the authority to say, ‘We’re going to focus on getting guns off the street rather than the drug case,’” Smith adds.

Jasmin McBride denies that she initiated the swap of guns for leniency. She denies she even had drugs and was not charged with possessing them.

The lawsuit allegations are now under review by the sheriff’s internal investigations division.

Officer Murphy declined to comment for this report.