The state prosecutor's office has launched an investigation into allegations that several elected officials and politically connected operatives in Prince George's County tried to shake down a developer who wanted to lease space to a county agency, according to a source familiar with the state probe.

Jonathan S. Shurberg, an attorney for developer Arun Luthra, said his client received a subpoena about a week ago to testify before a grand jury July 1.

"My client will be in front of the grand jury," Shurberg said. "He has been asked to, and he will go."

Deputy State Prosecutor Thomas M. McDonough said Wednesday that he could not confirm or deny whether an investigation is under way.

The state probe, first reported in the Gazette newspaper, is fallout from a civil suit filed in February by Luthra against County Executive Jack B. Johnson, a Democrat; Democratic County Council members Ingrid Turner, Camille Exum, Tony Knotts and Marilynn M. Bland; Johnson's top aide, Iris Boswell; lobbyist Michael Arrington; and commercial real estate broker Charles Dukes.

Luthra makes a wide range of allegations against the defendants, including breach of contract, fraudulent misrepresentation and intentional interference with business relations.

Luthra said he had several conversations with Johnson about the 10-year lease agreement, which amounted to more than $11 million. He said Johnson assured him that the agreement was a "done deal."

As a result, Luthra said, he began plans to prepare his building for the new offices, which cost him more than $890,000.

John Erzen, a spokesman for Johnson, said county policy is not to respond to continuing litigation.

Luthra alleges that after reaching an agreement with the county, he was approached by Dukes, who said that the lease agreement would "under no circumstances" be approved by the County Council unless Luthra paid him a 3 percent commission, totaling $341,000, up front. Luthra did not agree to the commission.

"That's absolutely untrue," Dukes said the accusation that he requested a commission.

Dukes said that he is unaware of a state investigation and that he has not been subpoenaed. He added that he knew about the lawsuit filed by Luthra but that has not been served in the civil suit.

Dukes said he met Luthra when Pam Piper, former director of Central Services, asked him to go to an initial meeting to discuss county leasing. He said that he has represented the county in leasing negotiations but that he never became involved in this lease agreement.

Luthra said that Arrington then approached him and told him that he knew about the bill before the council, and that he would like Luthra to make a $50,000 contribution to the Prince George's County Presidential Inaugural Committee, which was allegedly run in part by Exum, Bland and Boswell. After speaking with his attorney about whether the contribution was legal and what the maximum amount of the contribution should be, he donated $4,000, court records show.

Arrington then told Luthra that since he did not make the $50,000 contribution, he should hire him for $5,000 a month to lobby the council, Luthra alleges.

Arrington did not return a call seeking a comment.

Luthra said that Knotts came to his business and discussed the lease with one of his employees, Parvez Ahmed. The lawsuit alleges that Knotts told Ahmed that Luthra wanted the bill to be considered, but that before that could happen, Luthra would have to find 10 "diamond members" for a fundraiser for Knotts on Sept. 29, 2009.

"A diamond member is one who contributes $4,000, the legal maximum under Maryland law, and therefore defendant Knotts was asking Mr. Luthra to raise $40,000 in return for his support of the bill," the lawsuit states.

Court documents say Luthra declined to raise the money.

Karen Campbell, a spokeswoman for Knotts, Exum, Turner and Bland, referred calls to Stephanie Anderson, the county's attorney. Anderson did not respond to two phone messages.