ANNAPOLIS, Md. (AP) — A Maryland state senator already indicted on charges that he accepted illegal payments while using the word "lollipop" as a code for every $1,000 he expected to collect was indicted again after investigators say he tipped off the target of a federal investigation, the U.S. attorney's office said Wednesday.

A federal grand jury indicted Sen. Nathaniel Oaks on an obstruction of justice charge. An attorney for the senator did not immediately return a call seeking comment.

Oaks, a 71-year-old Baltimore Democrat, had agreed to cooperate with the FBI by recording his conversations with the target of a new investigation. At the direction of the FBI, Oaks covertly recorded his telephone conversations and in-person meetings with the target from Jan. 9 until March 30, the U.S. attorney's office said. The target is not identified.

Oaks allegedly approached the target March 17 at a bar in Annapolis without recording or disclosing the conversation to the FBI, telling the target "what we talked about, just say no."

Oaks again allegedly approached the target in the hallway of a state government building in Annapolis and said: "I'm going to ask you for something, just say no."

The indictment alleges that the statements were intended to dissuade the person from engaging in the activity that was the subject of the criminal investigation, the U.S. attorney's office said, adding that Oaks and the person had discussed the activity in a recorded conversation earlier that day.

The target understood from Oaks' statements on the two days that the senator was warning him not to engage in the activity because there was a criminal investigation underway, prosecutors said.

The original indictment earlier this year charged Oaks with wire fraud, honest services wire fraud and violations of the Travel Act for allegedly accepting illegal payments in exchange for using his official position to benefit an individual on business-related matters. His trial is scheduled for April.

In the initial case, when a cooperating source asked Oaks how much the senator should be paid for filing a $250,000 bond bill for a project, he asked the lawmaker: "How many lollipops should I bring," a question Oaks avoided answering directly, saying he had faith in him. An affidavit says the source and Oaks had established the word "lollipop" as a code word for $1,000, stemming from the time he put a Tootsie Pop in his mouth to halt open discussion of monetary amounts.

The case stems from an investigation dating to 2015, when Oaks was a member of the House representing a district in Baltimore.

Oaks represented Baltimore in the House of Delegates from 1983 until early 1989. In 1988, he was convicted of theft and misconduct in office charges for stealing thousands of dollars from his re-election fund. He received a five-year suspended sentence and lost his House seat as a result. But in 1994, Oaks was re-elected to the House, where he served until February, when he was appointed to replace a senator who retired.

Oaks faces a maximum sentence of 20 years in prison for each count of wire fraud, 20 years in prison for honest services wire fraud and five years in prison for each count of the Travel Act. He also faces 20 years in prison for the obstruction of justice charge.