The subpoenas are being issued to 108 former LIRR employees who retired this year and are eligible for the Federal Railroad Retirement Board's occupational disability benefit, which disabled railroad workers receive instead of Social Security.

A report released last week by the federal Government Accountability Office said that in 2007, LIRR employees applied for the benefit at a rate 12 times higher than employees of other railroads, and that the Railroad Retirement Board approved nearly 100 percent of all disability applications.

Both the retirement board and the LIRR adopted measures last year intended to prevent possible abuses of the system by LIRR employees. But law enforcement sources said that state prosecutors so far have been dissatisfied with both agencies' inability to report progress since the measures were adopted.

"No one knows anything," said a law enforcement source close to the investigation. "You try to get any information and there is no clarity with respect to a problem that we identified more than a year ago."

Cuomo's subpoenas will require retirees to provide documentation of any alleged disability, the source said.

In October 2008, the retirement board adopted a five-point plan it said would prevent LIRR retirees from gaming the system. The plan included increased medical screening of retirees applying for disability benefits and closer oversight of their cases.

About the same time, the LIRR implemented a plan to prevent disability pension abuses through increased ethics training and greater internal oversight.

Nevertheless, the GAO report last week said that the Railroad Retirement Board approved 64 of 66 claims by LIRR employees from last October until April of this year.