FEW NAMES evoke in Washingtonians the sense of loathing that comes with the mention of Bernard Welch. If you lived in this area five years ago you will remember that Mr. Welch amassed a fortune in stolen goods -- the fruit of countless burglaries -- before he murdered one of the city's leading citizens, Dr. Michael Halberstam. The crime was dramatic as well as tragic, for the victim managed to follow the killer and run him down with an automobile minutes before dying of gunshot wounds. And the discovery of a treasurehouse of valuables at Mr. Welch's home in Great Falls, Va., increased the number of area residents who realized that they, too, had been his victims. Was he sorry? Not this thug. "I had everything going for me," he told Life Magazine, but now "I'm in prison. They say I destroyed his life, but he destroyed mine."

Justice was done when the killer was sentenced to serve a minimum of 143 years in federal prison for Dr. Halberstam's murder and an assortment of other crimes. Penal authorities also took seriously his history -- he had once escaped from a prison in New York -- and his threats. Mr. Welch's lawyer, Sol Z. Rosen alleged that the prisoner had offered him $50,000 to arrange for incarceration at St. Elizabeths Hospital, from which he hoped to escape, and Mr. Rosen warned at the time of sentencing that the murderer "is of the opinion that he can break out of any prison and does not intend to serve his sentence." So he was sent to the federal penitentiary at Marion, Ill., described as the federal government's toughest and most exclusive lockup, surrounded by thick walls, double fences and concertina wire.

This week, Mr. Welch made good on his boast. After persuading law enforcement authorities that they could provide information about possible escape plans from other federal prisons, Mr. Welch and a confederate -- another convicted killer with an escape record -- were brought from Marion to a federal prison facility in downtown Chicago from which the two have now escaped. There are questions to be answered: Why wasn't the warden in Chicago warned about these men's histories? Why was there only one security guard on duty at the prison? Is it wise to allow dangerous inmates access to barbells -- which were apparently used to break a window? Is the design of the Chicago facility, which has tall, three-inch wide windows but no bars, wall, fences, guard posts or other security barriers, practical for an inner-city prison? These matters are the special concern of federal prison and law-enforcement authorities who will be examining prison policies and making changes in light of this foul-up. The citizens of the Washington area have a more immediate demand: they know this man and what he is capable of doing -- they want him found and put securely behind bars.