Fairfax County police announced two weeks ago that they had solved 300 burglaries that occurred during the last two years in 10 subdivisions in the Mount Vernon area of the county.

According to police, they solved the cases after a nine-month investigation that included "a lot of overtime and sleepless nights," numerous meetings with sources, late-night stakeouts, police lineups, the arrest of three suspects last November, and the confession of one suspect who admitted he had committed the 300 burglaries.

Larry Dade, the suspect who admitted to committing the 300 burglaries although he was charged with only 11 of them, said he "confessed" to the burglaries only as part of a bargain to receive a lighter prison sentence. Dade denies that he committed any of the 300 burglaries, including the six to which he pleaded guilty.

Police and Dade tell differing versions of how the 300 burglaries were solved. Police said Dade pointed out the homes that he burglarized, some of them more than two years ago while cruising in a police car through various subdivisions on March 16 and 17. Dade said police took him to various subdivisions and asked him if he broke into any homes in the area and Dade said he replied "six or seven here . . . maybe nine or 10 here. To get rid of 11 years I would tell them anything." Police denied Dade's accusation that the confession to the 300 burglaries only came as part of the bargain for a lighter sentence.

Dade, an admitted 23-year-old drug addict, said he was told by police that if he helped them solve the 300 burglaries they would recommend that he receive a 20-year prison sentence for pleading guilty to the six burglaries with 11 years suspended.

According to police, Dade told them about the 300 cases after an assistant prosecutor had recommended the nine-year sentence for Dade on March 14, the date he pleaded guilty to the six burglaries. Five other burglary charges were dropped.

Assistant Fairfax Commonwealth's Attorney Dudley H. Payne Jr. said he recommended that 11 years of the 20-year sentence be suspended in exchange for the guilty pleas.

"I recommended the sentence that I did based on what I saw as a fair disposition of the case," Payne said. "It was inherent in that recommendation that he (Dade) would clear up the other 294 cases, but it was not put in the plea agreement.

According to police investigators Jimmy Stone and Frank Bradley, the arrest of Dade, who lived at 2823 Mackell Ct., south of Alexandria, and two other suspects last November culminated the nine-month investigation that had focused on a gang of six or seven suspects in the Groveton area.

The two investigators said numerous burglaries occurred between January, 1975, and November, 1976, in the Sequoyah, Hollin Hills, Hollin Hall, Riverside Estates, Stratford Landing, Villa May and Waynewood subdivisions and the Audubon, Oak Grove and Harmony trailer parks.

The investigators said the burglaries of the homes usually occurred during the day while residents were at work, while the breaks-in of the service stations and other businesses occurred at night.

When Dade appeared in court on March 14 for a hearing on the first of the 11 charges, he pleaded innocent. However, after hearing the evidence in the case, which involved the burglary of an Exxon station at 7635 Richmond Hwy. last July, Dade changed his plea to guilty.

In an interview in the Fairfax County jail, Dade said he is innocent of all the burglary charges. He claimed he was with his girlfriend at the time of the burglary of the Exxon station. His girl friend testified at the trial that Dade was with her.

Dade said he changed his pleas before the jury was about to deliberate his fate because his court-appointed lawyer, Ben Warthen, advised him that the evidence was against him and that he could possible get a lighter sentence if the pleaded guilty. Warthen said he did advise Dade that the evidence was not in his favor and he could plead guilty.

"I was ignorant of the law," said Dade. "My lawyer was telling me they [the jurors] are going to convict me. I decided to cooperate."

After pleading guilty to the six burglary charges, Dade said he admitted to the other 294 burglaries since the police and prosecutors said he would not be charged with the offenses.

"They don't have any concrete evidence against me" in the 300 cases, Dade said.

Police said they did not recover any of the stolen property in the 300 cases, which included cash, guns, stereos, television sets and jewelry, because most of the property was taken to the District immediately after the burglaries and sold.

"We had one goal in mind - protecting the community by getting these guys off the street," Bradley said. "The 300 cases were a bonus."

The two other suspects, Sammy Furgenson, 25, of 7803 Belford Dr., south of Alexandria, and Jerry Sellers, 23, of 8000 block of Fordson Rd., were involved with Dafe in some of the burglaries, police said.

On March 2, Furgenson was found guilty in Fairfax Circuit Court of two burglaries and sentenced to nine years in prison. A day later, he was found guilty of being an accessory ofter an armed robbery and sentenced to nine additional months in prison.

Sellers was convicted on March 4 on two counts of burglary and sentenced to five years' imprisonment. He also is awaiting trial on robbery, abduction and malicious wounding charges.