A former legislative aide to Northern Virginia Rep. Frank R. Wolf testified yesterday that he attacked his next door neighbor with a meat cleaver in self-defense last Christmas night after the neighbor became belligerent and threatened him.

The victim contradicted that testimony in Fairfax County Circuit Court and called the attack by legislative aide Sewall K. Hoff, 40, unprovoked.

"I was saying good evening," testified Richard J. Andrews, 32, and was leaving Hoff's home "when Mr. Hoff struck me in the head with a meat cleaver." The attack left a gaping, 5 1/2-inch wound in Andrews' forehead, according to court testimony.

Hoff told the jury that he grabbed the meat cleaver in self-defense after Andrews lunged at him. He said he thrust the blade between them and Andrews head "struck the blade."

Both men testified at Hoff's trial that they had been drinking beer and tequila for more than two hours before the incident.

Judge Richard J. Jamborsky refused to allow newly discovered testimony from county rescue workers who told prosecutors that when they arrived at the scene of the incident Hoff allegedly told them he hoped that he had killed Andrews. Jamborsky told attorneys he would reconsider whether to allow the jury to hear the rescue squad testimony today.

The case before the five-man, seven-woman jury hinges on the credibility of Hoff and Andrews, who offered divergent accounts of the bloody incident at Hoff's Cavendish Drive house late last Christmas night.

In an effort to boost Hoff's credibility, Wolf made an unusual courtroom appearance to testify as a character witness for Hoff who worked in two of his congressional campaigns and had been employed as a staff computer operator. Hoff resigned in December after he was charged with malicious wounding.

"I believe very deeply that he has always told the truth," Wolf testified. Under cross-examination, Wolf said: "I have never caught him in a lie."