District of Columbia corrections officials announced yesterday that they will launch a formal investigation into how a convicted bank robber escaped Saturday from the D.C. Jail. The escape occurred when the inmate, who had been assigned to a trash detail, overpowered a guard, scaled a fence and eluded the jail's on-again, off-again electronic surveillance system.

Corrections Department spokesman Leroy Anderson said a panel of three to five officials within the department will be appointed soon to look into the escape by Rodney Patterson, 31, who had been sentenced recently to serve 8 to 24 years for bank robbery and was awaiting transfer to Lorton Reformatory.

The escape also brought renewed complaints from the jail guards' union that they are understaffed and lack a reliable electronic surveillance system. American Federation of Government Employes shop steward Sylvia Hall said there are only 480 correctional officers to guard 2,200 inmates at the overcrowded facility. The jail was designed to hold about 1,350. She said the jail needs about 100 more guards.

Anderson said many of the surveillance cameras around the jail do not work, including one at the site of Patterson's escape. He said the panel will inquire into why Patterson was assigned to a job near the jail's outside fence and whether a pistol had been smuggled in to aid him in the escape.

Announcement of the investigation came hours after Patterson was captured Sunday night in Northeast Washington by FBI agents and charged with kidnaping a Maryland woman and demanding $25,000 ransom during the 37 hours he was out of jail.

Federal prosecutors said yesterday that within the next 15 days they will seek indictments against Patterson on escape charges in Washington and kidnaping charges in Maryland. Patterson was held in the central cell block at D.C. police headquarters Sunday night and returned to the D.C. Jail yesterday.

At about 7 a.m. Saturday, according to Anderson, Patterson was working on a clean-up detail near a loading dock just inside a jail fence. He overpowered the single guard assigned to watch him, shoved what felt to the guard like a pistol into the guard's side and manacled him with his own handcuffs, Anderson said. Patterson then scaled the fence and fled, he said.

Within a few hours, FBI agents in Baltimore received a report that Paulette Lovett, 31, had been kidnaped by two men from her home in Woodlawn, a Baltimore suburb. The report came from Lovett's brother-in-law, Bernard Jerome Lee, a Baltimore County man who the FBI said has been convicted of narcotics trafficking in the past and was apparently an acquaintance of Patterson. The abductors demanded $25,000 ransom, the FBI said.

Lee, cooperating with the FBI, engaged in a series of telephone negotiations with the abductors and discussed several possible "drop sites" for the money in the Washington-Baltimore area.

It was while an FBI team was cruising one of the proposed sites near New York Avenue and Bladensburg Road in Northeast Washington that they spotted a car with Lovett inside and pulled it over. Two men ran from the car and one, later identified as Patterson, was tackled by the agents and placed under arrest. A second man in the car escaped on foot and was still being sought last night, the bureau said