A Prince George's County police canine officer investigating a 1993 break-in did not shout a loud warning before sending his dog into a Takoma Park home, where the animal mauled a nurse as she slept in her own bed, the victim's housemate testified today in U.S. District Court.

"There was no way I could have missed a loud announcement," Jonathan Lopez testified on the opening day of the trial of the civil suit filed by his housemate, Esther Vathekan, against Officer Jeffrey Simms. Vathekan is seeking $6 million in damages for her injuries and the $60,000 in medical bills she incurred.

Although Vathekan was seriously injured in the incident--the police dog sank its powerful jaws into the back of her scalp and chomped on the area around her right eye--the federal judge hearing the case has reduced it to the lone issue of whether police sounded adequate warning that the dog was being sent in.

Vathekan, 51, was asleep upstairs when the dog was released into the basement of the house on the afternoon of Jan. 10, 1993. Lopez had called police after discovering his door had been broken into.

Lopez's testimony contradicted testimony by Simms and several Takoma Park police officers, who each testified that Simms called out a loud warning before letting loose his police dog, Castro.

Simms testified that he stood in the back of the house, near the door leading to the basement apartment, which had been broken into, and called out, in a loud voice, "Prince George's County police canine. Come out or I'll let the dog in."

Vathekan's lawsuit is one of at least 13 pending civil cases alleging brutality and recklessness by the Prince George's County police canine unit. The FBI is conducting a civil investigation into whether the 23-officer canine unit has engaged in a pattern of brutality, and it has launched a separate criminal probe of a June incident in which a robbery suspect was bitten by a county police dog after he allegedly fought with officers and tried to run away.

After The Washington Post detailed the lawsuits and the broad FBI investigation in May, County Executive Wayne K. Curry (D) and Police Chief John S. Farrell announced changes that they said were designed to reduce the chances that the police dogs would engage in unnecessary and excessive attacks.

The county canine unit is now training its dogs to bark at suspects without biting them unless they flee or attack.

County police dogs have bitten hundreds of suspects in recent years, though Farrell has repeatedly refused to say exactly how many people the canines have attacked.

U.S. District Judge Frederic N. Smalkin, who is presiding over Vathekan's case, ruled that the only issue Vathekan and her attorneys can argue is whether Simms gave adequate warning before going in with his dog.

When Vathekan's attorney, Terrell N. Roberts III, tried to persuade Smalkin to let him call an independent canine expert to the stand today, the judge refused, saying, "This case is not about excessive force."

In his testimony, Simms, a 14-year veteran, said he waited a minute or so after giving warning before sending the dog in. However, some of the four current or former Takoma Park officers who testified yesterday said Simms let the dog into the house within seconds.

Castro found no one in the basement, Simms testified, then ran up the stairs leading to the first level of the house. There, Castro used his mouth to turn the knob of a closed door, then bounded into the room where Vathekan was sleeping, Simms testified.

While cross-examining Lopez, Associate County Attorney John Bielec, who is defending Simms, confronted Lopez with a report in which the young man had told police that he was not in a position to hear whether Simms called out a warning.

Lopez, however, insisted that nothing obstructed his hearing and that he would have definitely heard a loud warning.

Testimony in the trial concluded today. Attorneys will present closing arguments today, and the jury could begin considering the case before lunch.