KISSIMMEE, Fla. -

The Florida Department of Law Enforcement says as many as seven inmates have tried to use forged documents to escape from prison over the past couple of years and more arrests are imminent.

The revelation comes as investigators probe how two convicted Orange County killers, Charles Walker and Joseph Jenkins, were able to walk out of a Florida prison three weeks ago.

According to FDLE spokeswoman Gretl Plessinger, a confidential informant told investigators the phony court papers are being sold for as much as $8,000 apiece.

Plessinger says so far they have only identified three inmates who were successful in getting out of prison: Walker, Jenkins and a third man. Plessinger says the third inmate was caught one day later in Pinellas county. However, additional information on the third inmate's name, conviction and escape was not immediately available.

According to FDLE, a fourth inmate who unsuccessfully tried to use the same scheme was Jeffery Forbes. Forbes is serving a life sentence for trying to kill an Orange County deputy. Officials say his escape plans where thwarted this past spring by an alert detective.

Plessinger did not have an exact timeline on when all seven attempts were made, but she did say they all occurred over the past couple of years, and like Walker and Jenkins, five of the seven inmates were all housed at the Franklin Correctional Institution.

Plessinger said computers, printers and other office supplies have been confiscated from the Franklin prison as part of the ongoing investigation, but she did not know whether inmates, employees or both had access to that equipment. She said analysts are using touch DNA and other forensic tools as part of the investigation.

Plessinger added that FDLE investigators have identified suspects who helped Walker and Jenkins escape, but she did not know whether those suspects are other inmates, prison employees or people from the outside. She also said detectives are still working to identify whether those suspects are connected to any of the other known cases.

Plessinger said Walker and Jenkins are not cooperating with investigators, but their relatives are speaking with detectives.

The FDLE has scheduled a press conference for noon on Tuesday.