Maryland state police said yesterday they had arrested a father and son in Prince George's County and were investigating them for possible connections to a fraudulent check scheme that stretched from Maryland to Florida and into Alabama.

Acting on a tip, a team of undercover and uniformed state police from the Forestville barracks made the arrests Tuesday morning at the Knights Inn Motel in Capitol Heights, where the men had occupied three rooms. Among items confiscated by police were a payroll check-writing machine, numerous blank Social Security cards and a laminating device.

John Nathanial Coakley, 46, was picked up on separate warrants charging him with theft in Prince Frederick and Centreville, Md., possession of a .32-caliber handgun, and on detainers from several other jurisdictions. His son, William Vincent Coakley, 25, was charged with possession of small amounts of substances suspected of being marijuana and cocaine and possession of a .23-caliber handgun. He also was being sought by authorities in several states.

The Coakleys, who had no fixed address, were taken to the Prince George's County Correctional Center near Upper Marlboro and held on $7,500 bond each.

Police said the pair had a van that was confiscated in the motel's parking lot. Along with a well-stocked supply of food and clothing, police said the van also contained numerous phony identification cards, blank Social Security cards, blank birth certificates from the District, a payroll check-writing machine, a laminating machine and $13,000 in cash and coin. The cache included so many coins that a bank coin-counting machine was brought in to total the change, said state police spokesman Chuck Jackson in Pikesville.

Police in other states were notified of the arrests early yesterday, and Jackson said there was a strong response.

Police say John Coakley is believed to have used as many as 11 aliases, and more than 30 pieces of phony identification were found at the time of his arrest. The younger Coakley allegedly has used 29 names, police said, adding that officers found him with 45 fake identification cards.

Describing the check-fraud scheme under investigation in several Eastern Seaboard states, police said that real estate firms, automobile dealerships and other commercial businesses were broken into and blank payroll checks were taken. Police investigators suspect that the highly mobile operation was able to hit up to seven businesses per day, netting an estimated $2,000 daily. "Judging by the sophistication of the operation, we suspect, conservatively, that {it} has been in business for several months," Jackson said.