Prince George's County police officer Robert McDaniel wasn't sure what to think March 4 when he saw a stooped, white-haired man bent over his cane near the Pennsylvania Avenue exit from the Beltway. Fearing the man might be lost and would get run over, McDaniel, an auto theft investigator, picked him up.

The man turned out to be Daniel O'Brien, a spry, 87-year-old hitchhiker, on his way back from soggy California to Boston. O'Brien's only problem was that he'd run out of cash and his feet were sore and swollen, a result of diabetes.

O'Brien spent most of the rest of that Friday afternoon as a guest of the auto theft division while officers made fruitless telephone calls trying to find social service agencies that would help O'Brien get home.

The octogenarian carried no identification, but police were able to contact his nephew, a Boston police officer who lives in Woburn, Mass. The older man, who was wearing three sportcoats, two pairs of pants and a knit cap, told Sgt. Charles Ward that he was once a migrant farmer and had been hitchhiking most of his life. "The reason that he doesn't stay home was that he doesn't like being around old people," Ward said.

O'Brien's nephew, John O'Brien, said in a telephone interview that he put his uncle in a nursing home several years ago, but after a few months, the older man begged to get out.

Now, the nephew said, he just deposits the Social Security checks and his uncle comes back to Massachusetts about twice a year to pick them up.

The Prince George's officers collected $25 for O'Brien by early evening, and McDaniel took him to the Greyhound bus terminal in the District, where the bus company management helped him get back to Massachusetts.

The elder O'Brien arrived home, consumed a "huge steak dinner," got some sleep, collected his money and the next morning was out thumbing his way to Philadelphia, his nephew said.

"He's been all over the country a thousand times. . . . I guess he'll die on the highway."