Charles Walker and Joseph Jenkins, both 34, are considered "escapees" by authorities after being released from prison erroneously using forged documents.
Investigators discovered forged motions to reduce the duo's respective sentences and bogus court orders granting the request, according to reports.
A "vigorous and thorough review" will be conducted of other releases, officials say, to ensure that no others have been freed with falsified documents.
Both motions bore the forged signatures of the Orlando-area state attorney's office, a statement from Ninth Circuit State Attorney Jeffrey L. Ashton said.
The judge's order granting the release of Jenkins and Walker bore the forged signature of Judge Belvin Perry, coincidentally the judge in the Casey Anthony trial.
Ashton served as the case's chief prosecutor, and is now involved in more national headlines, as is Perry, who told CNN he wasn't entirely surprised.
"People, particularly with criminal minds, come up with ingenious ways to beat the system," he said. "They have nothing but time on their hands to think of things."
The orders to release the inmates were filed with the County Clerk's office, Ashton said. The documents, which contained the county seal among its markings, looked legitimate.
Ashton, meanwhile, ordered a review of records in an e-mail to prosecutors to determine if anyone else filed "similar forged documents or other suspicious activity."
Walker and Jenkins, both serving life without the possibility of parole sentences for murder, were released from the Franklin Correctional Institution in Carrabelle, Fla.
Jenkins went free on September 27; Walker was released on October 8.
It is unclear whether the two men knew each other, and the Orange County Sheriff's Office worries that at least one of them may have returned to the area.
Law enforcement learned of the escapes Tuesday after a family member of Jenkins' victim contacted the State Attorney's Office to ask about his release.
"These men committed violent crimes," Orange County Sheriff's Capt. Angelo Nieves told CNN. "The best thing for them to do is to turn themselves in."