A D.C. Superior Court jury yesterday acquitted a former nursing assistant at St. Elizabeth's Hospital of second degree murder in connection with the 1976 beating death of Robert Davis, 66, a patient at the federal mental hospital since 1943.

After a 12-day trial that included testimony from 26 witnesses, the jury reached a verdict after less than three hour deliebration.

Several jurors later told the defendant, Janice Little, 24, that the government had used her as a scapegoat to answer for Davis' death, according to one of her defense attorneys, Jay Bernstein.

Bernstein said jurors also told Little they intended to write letters to HEW Secretary Joseph A. Califano asking that the woman be reinstated in her hospital job with back pay and that Davis' death be investigated further. St. Elizabeths is run by HEW.

Little was dismissed from hospital in December 1976 when a federal grand jury indicted her three months after Davis' death. She has asked the Civil Service Commission to reverse that decision, her attorneys said.

On the afternoon of Sept. 18, 1976, an argument at the hospital began when Davis struck Little in the stomach after she asked him to get up off the floor near a cafeteria door and return to the ward.

Assistant U.S. Attorney Harry R. Bener argued that Little pushed Davis down after he hit her and then kicked him repeatedly. After the incident, Davis was placed in a locked cell, called a special treatment room, designated for assaultive patients. He died early the next morning and an autopsy subsquently revealed he died as a result of injuries suffered in a beating, according to testimony of city medical examiner.

"She (Little) kicked until she revenged herself" on Davis, who was an admittedly troublesome patient, Benner told the jury.

Fifty days after the incident, Little first disclosed she struggled with Davis, and admitted in a statement that she pushed and kicked him, Benner reminded the jury.

Little, who took the witness stand in her own defense, testified that she "kicked at" Davis, as she was doubled up with pain from the blow to her stomach, but said she was not sure that she had hit him.

Defense attorney Stanton Gildenhorn argued to the jury that Little acted in self-defense when she scuffled with Davis. Gildenhorn portrayed Davis as a former boxer, in relatively good physical condition who had a record of assaultive behavior at the hospital. The government prosecutor described Davis as a weak, 96 pound old man, a victim of a degenerative disease of the central nervous system since childhood.

The defense theorized that the seclusion room where Davis was held was left unlocked for about an hour during which time Davis could have been beaten by a patient.

A hospital employe testified that at 10:30 p.m., more than five hours after the incident with Little, he left the door to the treatment room unlocked, a disclosure Gilenhorn called "a bombshell."

Prior to that time, the employe testified, Davis was able to walk to the bathroom unassisted and appeared uninjured. That description, Gildenhorn told the jury, was inconsistent with the government's theory that Davis was severely injured by Little . . . a theory the defense attorney repeatedly described as "bull."