Two weeks before a 20-year-old man in suburban Philadelphia was named a “person of interest” in the case of four missing young men, prosecutors in Bucks County asked the police to arrest him on a previously dismissed felony weapons charge.

But the man, Cosmo DiNardo, was not arrested by the Bensalem Police Department on that charge until Monday, after the authorities had started scouring his family’s sprawling farm for any signs of the men who disappeared over two days last week. Mr. DiNardo was released from the Bucks County Jail on Tuesday evening after his father, Antonio DiNardo, paid 10 percent of his $1 million bond in cash, according to the county district attorney’s office.

For the fourth straight day on Tuesday, up to 50 people took part in a painstaking search on the farm — a vast property off a country road in Solebury Township, about 30 miles north of Philadelphia. The authorities brought in cadaver dogs and heavy construction equipment, including a backhoe, and led a careful examination of the land “not to miss the tiniest piece of evidence,” the county’s district attorney, Matthew D. Weintraub, said.

So far, the search had not turned up any human remains, but Mr. Weintraub declined to comment on whether other physical evidence connected to the missing men had been found at the site. Members of an F.B.I. evidence response team helped the local authorities search the property on Tuesday, said Carrie Adamowski, a spokeswoman for the bureau’s Philadelphia office.