An Annapolis man, arrested and released last January after police discovered a huge illegal drug-manufacturing laboratory on his farm, has been arrested again on charges of conspiring with an undercover agent to set up another lab for making the potent hallucinogen "speed," federal authorities announced today.

This time, Robert M. Krohn, 28, the son of a well-known Annapolis lawyer, was ordered held under $1 million bond by a U.S. magistrate. He was reported still in custody late today.

The arrest of Krohn and three other persons, including his girlfriend, Catherine Lee Scarborough, 27, came about this week after months of undercover work by a Drug Enforcement Administration agent, officials said. Baltimore DEA chief George B. Brosan said at a press conference that Krohn was arrested after he sold his chemical formula for "speed" (known officially as methamphetamine) to the undercover agent last March for $5,000.

Krohn was led to believe the agent was a drug dealer who could manufacture the synthetic drug at another laboratory in Chicago after Krohn's farmhouse lab in rural Ann Arundel County had been seized by county police in January, Brosan said.

In addition, Brosan said, a second suspect, Jack D. Holt, 35, of Leesburg, Va., was arrested after he arranged to sell dynamite, blasting caps and a detonating device to the undercover agent for a "booby trap" that would blow up the "Chicago laboratory" if authorities discovered it.

Holt was arrested Tuesday by local police and federal Bureau of Alcohol, Tobacco and Firearms (BATF) agents as he met the undercover agent at a motel in Ann Arundel County, Brosan said. Holt was charged with possession and manufacture of a bomb and released on $25,000 bond.

William Wildrick, chief of the BATF office in Baltimore, said Holt had suggested the dynamite be strapped to a 55-gallon drum of ether that would have set off an "enormous" explosion and fires.

On the same day Holt was arrested, a third suspect, Mauro Pasqualucci, 28, of Edgewater, Md., went to the motel to deliver $20,000 on behalf of Krohn for an initial purchase of "speed" from the Chicago lab, Brosan said. Pasqualucci also was arrested, charged with drug conspiracy and released on $5,000 bond.

Krohn and Scarborough were arrested the following night by DEA agents as the couple returned to their home on Barbud Lane in Annapolis. Scarborough was ordered held under $150,000 bond.

The arrests culminated months of investigation by federal agents who said they recorded a series of motel meetings between the undercover agent and the suspects on both video and audio tapes.

Krohn, whose father, Stanley, and brother, Stephen, are both lawyers in Annapolis, was first arrested--and then released on personal recognizance--last Jan. 14 when county police, looking for a missing person, accidentally discovered a large well-equipped drug lab on Krohn's farm near Davidsonville. Brosan described the lab as "one of the largest in the United States."

At a bond hearing Thursday before U.S. Magistrate Clarence Goetz, Krohn estimated the farm's value at $385,000. Court officials said Krohn also operates Atlantic Decal in Annapolis, which manufactures decals for T-shirts and car bumpers.

In arguing for the $1 million bond, assistant U.S. attorney William Quarles said Krohn had paid $65,000 cash last year for a printing press for his decal business and bragged of making $700,000 in four months from the sale of methamphetamine.

Methamphetamine is described in DEA literature as a powerful and dangerous stimulant and hallucinogen that often causes the user to "stay awake for days without food, undergoing hallucinations and bouts of paranoia, then lapsing into long, deep recovery sleeps."