Which Serial Killer Is Different?

[Fishface]

All of these guys were busted for serial murder. Please name the one whose case had a strikingly different LEGAL feature, meaning I am not asking about the killer's M.O., religion or hair color:

A) Tony Walker
B) Art Shawcross
C) Coral Eugene Watts
D) Colin Pitchfork
E) Willie Pickton

[Lee]

Colin Pitchfork was caught by DNA evidence,the first time it was used to convict somebody

[Fishface]

True, but not what I was after! BZZT!

[Lady ♥ Belleza, Gif Princesa]

Coral Eugene Watts was serving time for a murder in Texas, due to be released in 2006, in 2004 Michigan tried him for a murder there and were able to use the confessions he had made in Texas during the trial.

[Fishface]

True, but not what I was after! This can be answered in 2 words, peeps. Bel: the full and correct answer is implied in the answer you just gave.

[Koren]

They all served time for a previous murder and were released?

[Fishface]

BZZT but you are soooooooooo close.

[Lady ♥ Belleza, Gif Princesa]

Previous conviction

[Fishface]

BZZT....Koren is the closest so far.

[Lady ♥ Belleza, Gif Princesa]

Double jeopardy

[Shelley]

They had been picked up prior to their final arrest but were released with no charges against them.

[Fishface]

BZZT and BZZT!

[Shelley]

They received reduced sentences/charges in a plea bargain by agreeing to confess to other crimes and give details.

[Fishface]

BZZT!

[Shelley]

Similar transactions.

[Fishface]

BZZT! Koren is still the closest.

[Koren]

They were out on parole?

[Fishface]

Close enough, because the suspense is killing me -- DING DING DING! They were all known to be serial killer but were still eligible for parole.