The question of Carter's actual guilt or innocence remains a strongly polarizing one, however this much is certain: either the criminal justice system released a triple murderer from the punishment that two separate juries had recommended, or it imprisoned an innocent man for almost 20 years.

While in prison, Carter resumed his interest in boxing, and promptly upon his release in September 1961, turned professional. At 5 feet 8 inches, Carter was shorter than the average middleweight, but he fought all of his professional career at 155-160 pounds. His shaven head, prominent mustache, unwavering stare and solid frame made him an intimidating presence in the ring decades before such a look became commonplace. His aggressive style and punching power (which resulted in many early-round knockouts) drew attention, establishing him as a crowd favorite and earning him the nickname "Hurricane". After he had beaten a number of legitimate middleweight contenders such as Florentino Fernandez, Holley Mims, Gomeo Brennan, and George Benton, the boxing world took notice. Ring Magazine first listed him as one of its "Top 10" middleweight contenders in July, 1963.

He fought six times in 1963, winning four of the fights and losing two.[1] He remained ranked in the lower part of the top 10 until December 20, when he surprised the boxing world by flooring past and future world champion Emile Griffith twice in the first round and scoring a technical knockout.

That win resulted in Carter being ranked as the #3 contender for Joey Giardello's middleweight title. Carter won two more fights (one a decision over future heavyweight champion Jimmy Ellis) in 1964, before meeting Giardello in Philadelphia for a 15-round championship match on December 14. Carter fought well, but the judges awarded Giardello a unanimous decision. Most of the press concurred; an informal poll conducted among sportswriters at ringside showed that 14 of 18 agreed that Giardello had outboxed the challenger. Carter was gracious in defeat and did not protest the judging.

After that fight, Carter's standing as a contender�as reflected by his ranking in Ring Magazine�began to decline. He fought nine times in 1965, but lost four of five fights against top contenders (Luis Manuel Rodriguez, Harry Scott and Dick Tiger). Tiger, in particular, had no problem with Carter, flooring him three times in their match. "It was", Carter said, "the worst beating that I took in my life - inside or outside the ring".