Greg Lawson reacted "laughing" as he handcuffed him and asked police officers sarcastically: "How are you?"
Lawson, 63, fled from Louisiana, United States, before a jury convicted him of shooting a man, Seth Garlington, in 1991 in a parking lot outside a gas station.
In a video on Twitter previously on X, Lawson is seen wearing a short-sleeved shirt and camouflage hat and accompanied by police officers, then patting someone on the shoulder while laughing, before an officer handcuffed him.
Douglas Williams Jr., the FBI's agent in charge of New Orleans, said the arrest would not have been possible without the help of authorities in Mexico.
"We want to thank our partners who have never given up hope that justice can be done for Mr. Lawson's victim," he said.
The FBI said it had always suspected Lawson was hiding in Mexico, and information he received earlier this month confirmed his theory.
Lawson was arrested on Tuesday, September 19, and detained in Louisiana.