A D.C. Superior Court judge who was criticized last week for releasing a murder suspect on bond said yesterday that there were "significant problems" with the government's evidence in the case.

In an unusual defense of his release of 26-year-old Debra Lavinia Finley, Judge Frank E. Schwelb said that, although there was "probable cause" to believe Finley participated in the Oct. 20 slaying, he had "grave reservations" about the reliability of some of the evidence introduced by the prosecution at a preliminary hearing last week.

Finley was charged last week with first-degree murder while armed in the killing of Gary Ballard of Southeast Washington, who was found lying on the floor of Finley's Half Street SW apartment with 25 stab wounds. Finley originally was held without bond.

"While reasonable people might differ as to the strength of the evidence against her, there are significant problems with it," Schwelb wrote in a 13-page memorandum.

The U.S. attorney's office declined to comment yesterday on Schwelb's memorandum. Last week, prosecutors vigorously objected when Schwelb released Finley, who is pregnant, on $20,000 bond. At the time, Assistant U.S. Attorney Wallace Kleindienst argued that Finley was a danger to the community and might flee to avoid prosecution.

Yesterday, Schwelb noted the eight-month delay in the arrest of Finley in assessing the government's arguments that Finley should continue to be held without bail.

"Knowing most of what they now know for more than eight months, police and prosecutors left Ms. Finley at liberty and charged her with no crime," Schwelb wrote.

A man previously charged in the slaying of Ballard died of cancer four months ago while in custody. Police sources have said they believe the man, Charles Canty, may have agreed to take sole responsibility for the allegedly drug-related slaying because he was terminally ill.

In his memorandum, Schwelb questioned in particular two events described by prosecutors as part of their case against Finley.

First, he wrote, he had "grave reservations" about a statement given to investigators by a man who said Ballard had telephoned him the day of his death and said "they are trying to kill me" before the phone was slammed down.

"It is difficult to imagine brutal and sadistic murderers allowing their victim to initiate such a call," Schwelb wrote.

Schwelb said also that he was bothered by accounts from witnesses that on the day before Ballard's death, Finley had chased him down the street with a knife, threatening to kill him.

"The court is somewhat perplexed by the suggestion that Ballard would come unarmed to Ms. Finley's apartment the day after . . , " Schwelb said. "Under ordinary circumstances, people do not act in that way."

At the time of last week's hearing, the prosecution also noted that since Ballard's death another man, Neil Jones, had died in Finley's apartment of a drug overdose. Police said Jones' death is being investigated as "suspicious."