Timothy Joseph Buzbee, convicted of two rapes in the Aspen Hill area of Montgomery County, was sentenced yesterday to a third concurrent life term in prison moments after he acknowledged for the first time in open court that he needs help before he can return to society.

The 26-year-old land surveyor, whose only previous public statement since his arrest was his avowal of innocence on the witness stand in his first trial, stood in a Montgomery County courtroom yesterday and told the judge: "I would hope through the rehabilitation system . . .I could get some help and when the time is right I can return to society and help bring up my kids."

Circuit Court Judge John F. McAuliffe then imposed sentences of life in prison and 20 years to run at the same time as Buzbee's sentence of life plus 50 years in the first Aspen Hill rape case. This means that, with all possible time off for good behavior, Buzbee would first be eligible for parole in 24 years.

Although Buzbee is charged in two other Aspen Hill rape cases, scheduled for trial Oct. 7, it is unlikely he will be tried in those cases, according to his defense attorney, Reginald W. Bours III.

Sources said that Bours and prosecutor Barry Hamilton are working on a plea agreement that could bring those cases to an end without trial. Neither side would comment on details of those negotiations, and any such agreement would have to be approved by a judge before it became final.

Disposition of those two cases would bring to an end nearly two years of investigation and trials that stemmed from the series of rapes that had terrorized the upper-middle-income Aspen Hill community.

Yesterday, after imposing sentence, McAuliffe said he would cooperate with defense requests that Buzbee be evaluated by a team of doctors at Johns Hopkins Hospital in Baltimore for participation in a program designed to help sex offenders.

The program employs psychological therapy and injections of Depo-Provera, a controversial drug designed to change hormonal balance and lower sex drive. Some inmates at the maximum-security Maryland Penitentiary already participate in the program while incarcerated. Dr. Fred Berlin, a psychiatrist who directs the program, has interviewed Buzbee once, and in a letter referred to in court, recommended treatment that would include the drug.

As McAuliffe prepared to sentence Buzbee for the kidnaping, robbery and rape of a 39-year-old woman, he said he faced the difficult task of balancing the crime of rape--"one of the more atrocious and serious with which we deal"--against "the character and person of Timothy Buzbee."

He said letters from Buzbee's family, friends, teachers and associates had shown Buzbee to be a "very fine father" to his two young daughters, a thoughtful friend and an industrious worker who often held down two jobs at a time.

"It is one of the great mysteries of this case how Timothy Buzbee ever came to be involved with a crime of the type we here deal with," McAuliffe said.

But McAuliffe also said that evidence seized in the cases showed Buzbee to have "a kind of obsessive voyeuristic tendency" that, he said, in retrospect turned out to be "extremely disturbing."

Finally, the judge asserted, "No sentence less than life in prison would be appropriate." But McAuliffe did not make that sentence consecutive to the life term Buzbee received in his first Aspen Hill rape conviction, asserting that it was not appropriate to believe "there is no possible hope for rehabilitation, no light at the end of the tunnel."