"Bigfoot" they called him.

And for at least three hours yesterday afternoon a posse of about 30 U.S. Capitol police officers and two police dogs swarmed over the dark, stifling attic of the Longworth House Office Building, stalking what they thought was a trapped, barefoot intruder in hiding.

All they got out of it was dirty uniforms.

"He had feet tha-a-a-a-t long," said Sgt. G. R. Salyer, spreading his hands to about the size of a 15 triple E.

Salyer, one of only two searchers who actually saw him -- another heard him trying to open a locked door -- said he chased the elusive suspect down a narrow attic catwalk before losing him.

Reinforcements were brought in from the Senate side to help comb the 46-year-old, block-long building at New Jersey and Independence avenues and Salyer described their quarry this way: ". . . cutoffs, no undershirt, large feet. The biggest feet I've ever seen."

The episode disrupted the solitude of the House recess as bands of officers in hot pursuit shouted to startled congressional aides to close their doors and stay out of the halls.

It all began about 3 p.m. after building employes reported seeing a scantily clad man in the attic. Two officers stationed in the building joined a mantenance man going to make a routine check of the attic, a dark rabbit warren of dusty airconditioning ducts snaking all over the floor.

Officer F. K. Mucker turned his flashlight on a corner. The maintenance man and Salyer said they saw "Bigfoot." Mucker said he didn't. All three gave chase and then called in help when they lost him amidst the duct work.

Some officers searched rooms and hallways on the seventh floor, just below the attic. Others searched the rooftop as strains of "The Battle Hymn of the Republic" wafted up from a chorus singing on the grounds of the Capitol.

About 7 p.m., frustrated officials called off the search.

Inspector Eugene Rucchio said a large piece of cardboard that looked like someone was using it for a bed was found, but said reports of someone "living up there" appeared not to be true. Other officers mentioned several recent thefts in the building and speculated that the man they chased might have been a thief using the attic as a hiding place.