The FBI has arrested an ex-convict accused of plotting to execute Robert Jenkins, a well-known New Orleans defense attorney, in a murder-for-hire scheme involving one of Jenkins’ former clients.

The suspect, Kenneth Lee, was taken into custody in Maryland last week after federal authorities conducted a sting operation and used GPS tracking to pinpoint his cellphone, according to court records.

The authorities said the plot was hatched earlier this year at a federal prison in central Florida, where until recently Lee had been serving time alongside Donald Sylvester, who was sentenced to life behind bars for a 2003 contract killing in New Orleans of a witness in a federal drug case.

Sylvester fired Jenkins before going to trial and later complained that his pretrial representation — during which Sylvester confessed to his role as triggerman — had been ineffective.

“Once it unraveled, he realized the mistake that he made,” Jenkins said in a telephone interview Tuesday, recalling Sylvester’s confession and later insistence upon proceeding to trial.

Jenkins said he was “very concerned” about the alleged murder-for-hire plot but not unaccustomed to threats in his profession, particularly in high-profile cases. “I’ve been through it many times,” he said.

Lee had been sentenced to 15 years in prison under a law known as the Armed Career Criminal Act for committing a series of “serious drug offenses” as well as a burglary in Maryland. But that term was reduced considerably in September to reflect a recent U.S. Supreme Court ruling that, when applied to Lee’s case, prevented prosecutors from counting the burglary conviction as a “violent felony” under the career criminal law.

Shortly before his release, authorities said, Lee approached Sylvester at the Coleman Correctional Institution in Florida and asked whether Sylvester would like anyone to be murdered in retribution for testifying in his proceedings. Sylvester later acknowledged to federal authorities that he accepted this offer as it pertained to Jenkins. At some point, he agreed to cooperate with the FBI investigation and keep in contact with Lee.

The authorities reviewed an Oct. 16 call between Sylvester and Lee in which the two held “a coded conversation about how Lee would carry out the murder-for-hire,” FBI Agent William C. Williams wrote in a criminal complaint.

“I don’t have to do anything more,” Lee allegedly said at one point during the call, “just be in the right spot.”

Sylvester told Lee he would get him in touch with his uncle in New Orleans to arrange him “a nice gig,” promising the uncle would help him out and show him the city, the complaint says. According to the FBI, Lee understood that the uncle, supposedly a fitness trainer, actually would provide him with the weapon to kill Jenkins and compensation after the hit was executed.

Earlier this month, an FBI agent called Lee posing as Sylvester’s uncle, the complaint says, and said he assumed that Lee, having just come home, might be “light on equipment.”

Using a code referencing different calibers of handguns, “the (agent) stated to Lee that he had an entire gym and equipment which included 9- and 40-pound weights and 45-pound plates and asked Lee if he had a preference,” Williams wrote in the complaint. “Lee stated that he could use anything and that he did not have a preference. He stated that he had been working out for years.”

The agent called Lee again on Dec. 21 and Lee said he was “still interested in doing the job,” the complaint says, “and indicated that he wanted to do it within the next few days.”

Mary Beth Romig, an FBI spokeswoman, said Lee was arrested Dec. 23 after he picked up a package the undercover agent had sent to him in Balitmore as an advance for the murder. She said the FBI had determined Lee had “the capabilities and desire to carry out the plot.”

Jenkins said Tuesday he never felt his life was in danger and that the authorities had notified him of the sting more than a month ago.

“The FBI and the U.S. Attorney’s Office were on top of it, and they kept me briefed about it,” he said. “They did a wonderful job of keeping me abreast of what was going on.”

Jenkins said he has taken certain security precautions of late, which he declined to specify.

Jenkins has handled a number of high-profile criminal cases, including the recent corruption cases of former New Orleans Mayor Ray Nagin and former Jefferson Parish President Aaron Broussard.

Follow Jim Mustian on Twitter, @JimMustian.