Prince George's County police violated the legal rights of two key witnesses and a defendant in the recently concluded investigation of a highly publicized quadruple murder at a Landover liquor store in 1974, according to testimony taken in court this week.

The two prosecution witnesses testified at a preliminary hearing that police held them for several days without warrants while questioning them to obtain information that led to the arrest of two men charged in the case.

One of the witnesses, John W. McRae, testified that county police "slapped me around" before questioning him.

The other witness, James Lucas, a convicted narcotics dealer and user, testified that he was questioned by county police after being held in jail for three days without access to drugs. In this condition, he testified, he could have been "easily led" by his interrogators. "It affects my nerves. I want to sleep. I don't want to be bothered" when deprived of drugs, he testified.

Assistant State's Attorney Edmond B. O'Connell said he asked police about the allegations and that they told him "there was none of that." Police refused to comment specifically on the testimony except to say that "we do not hold people against their will without warrants and we do not beat witnesses."

Judge James Magruder Rae was also told that one of the two men charged with the crime. Thomas Butler, had been held in custody too long by police without a hearing. The judge threw out Thomas Butler's confession as a result.

Judge Rae said the confession had been taken in violation of laws which require police to take the defendant before a Commissioner within a reasonable period of time.Butler was arrested and charged on Dec. 16, but was not taken before the commissioner until Dec. 17 after more than 10 hours of interrogation.

The testimony raising questions about the county police handling of the case came at a preliminary hearing for Butler, 30, and his brother, James Calvin Butler, 32, both of 3580 Hayes St. NE. They are charged in connection with the 1974 slayings of a Landover liquor store owner, his wife and two delivery men during a holdup.

The two brothers were arrested last month after a gun that was allegedly stolen during the 1974 holdup surfaced in an unrelated robbery in the District. Police said they traced the gun to Thomas Butler.

One of the witnesses, Lucas, said he received the gun from Thomas Butler. Lucas testified that he was held five days by Prince George's County police investigating the murder without any formal charges being placed against him.

He said he was kept in an interrogation room for three days where he slept with his head on a table in between interrogation periods.

McRae, the second witness who reportedly heard Thomas Butler discuss the robbery, said to be the driver of a gateway car in the liquor store holdup, said the police "slapped me around" as they took him to the county Bureau of Criminal Investigation for questioning. "I thought they were going to kill me. I didn't see myself coming out of that room no time soon," he responded under questioning by defense lawyers.

He testified that he was held three days without a warrant of formal charges being placed against him after he was taken by police.

Defense attorneys were also upset by the fact that during questioning police had reminded some of the witnesses about the $5,000 in reward money offered for the conviction of the perpetrators by one of the victim's relatives. MaRae said police told him: "You know about the reward don't you."

The Butlers, along with an unnamed third suspect who is still being sought, are accused of killing R. Earle Sheriff Sr., the 82-year-old owner of the Kent I Village Liquors, his 75-year-old wife Clara, and two delivery men for a wholesale liquor distributing company, William E. Deetz, 20, and Melvin F. Montgomery, 22.

Police sais shortly before 8 a.m. Oct. 24, 1974, holdup men forced Sheriff and his wife into a walk-in cooler and took the delivery men to a back room. Deetz was handcuffed to a pipe on an ice machine.

Police said the armed men then ransacked the store probably in search of money Sheriff used to cash checks and make small loans.

The Sheriffs were then taken to the back room where all four victims were doused with a flammable liquid and set ablaze. Montgomery, who apparently tried to flee, was found shot in the back.

It was the fire, according to police, that alerted passersby who called the authorities.

When the police and fire department arrived, they found the windows of the store blown out by the fire and the charred bodies of the victims in the back of the stores. Mrs. Sheriff and Deetz were dead when police arrived and Montgomery died later at Prince George's General Hospital. Sheriff also died 6 1/2 hours after the incident, but was able to give a discription of the robbers and details of what happened to police.

Sheriff once had been a Prince George's County sheriff. That career ended in 1950 when he was indicted for taking protection money from gamblers and for tax evasion. He spent a year and a day in prison for tax evasion.

"We will totally review what happened during the course of the preliminary hearing and then decide in the next couple of days where we go from here," said O'Connell who will have a number of alterntives before deciding whether to go futher with the prosecution.