More than 300 investigators searched the New York City area today for a couple wanted in connection with an extortion attempt on the makers of Tylenol. They were seen in New York as late as last Thursday, an FBI spokesman said today.

The couple, identified as Theodore Elmer Wilson and his wife LeAnn -- who also have been known by the name Lewis as well as many as 20 other aliases--checked into the Rutledge Hotel at 161 Lexington Avenue on Sept. 6, 23 days before the Chicago deaths began, and lived there until Oct. 14, the FBI said.

Police say that the extortion letter sent to the makers of Tylenol was sent from New York City. The couple stayed in the New York hotel for $95 per week, paid in cash in advance, until last Thursday, investigators said. On Monday, tentative reports placed the couple in southern Missouri, including the town of Carl Junction, Wilson's home town, but investigators said they think it is still likely that the couple is in the New York area.

Police are monitoring air, rail, and bus transport out of the city, and are looking for a 1969 American Motors Ambassador with Missouri license plates, the last car the couple was known to have had when they lived in Kansas City a year ago.

Chicago Police Superintendent Richard Brzeczek said no evidence has been found so far to connect the couple to the deaths of seven people in Chicago from cyanide-tainted Tylenol, but a warrant for their arrest in the extortion case has been issued.

The Wilsons entered the case officially a week after the Chicago deaths, when a handwritten extortion note was opened in the New Jersey headquarters of Johnson & Johnson, parent company of the firm that makes Tylenol. The letter said that if the company wanted the killings to stop, $1 million was to be deposited in an account at the Continental Illinois Bank and Trust Co.

The account belonged to a Chicago businessman who had not long before fired LeAnn Wilson from his now-closed Lakeside Travel Agency. Later, Mrs. Wilson sued the businessman for back wages, but lost the case.

The extortion letter bore the businessman's name.

But police said they found Theodore Wilson's fingerprints on the letter, and also found the writing similar to a sample of Wilson's writing police have.

Police believed at first that any scheme had been designed to embarrass the businessman who fired Mrs. Wilson, and was not intended to get money from the company. Police said today that since the account was one from which money could be transferred to a foreign account, it is conceivable that getting money was actually the object.

But one knowledgeable Chicago police official said, "I don't buy that idea. If he had some way of getting a code and transferring money out of somebody else's account, he wouldn't need to write an extortion letter at all." The idea that the extortion note was a hoax also fit well with descriptions of those who had known Wilson in the 10 months before the Tylenol tragedy.

In a rooming house on Chicago's North side, he entertained friends and neighbors with his dreams and schemes. The schemes, said Thomas Kline, the rooming house manager, were of different kinds -- some for fun, some imagined profits, and many were designed to get revenge.

"He was a very smart guy. And he liked to laugh," Kline said.

He told Kline, his landlord, how he would get revenge against a landlord he did not like -- by planting near the building's boiler an explosive can such as one full of propane, placing it in the summer and waiting until winter for it to explode.

Thomas Bullistron, who lived upstairs from Wilson, spent many hours listening to him talk about schemes to alter deeds and sell a house several times before fleeing with deposit money, or a scheme to steal bank papers that would allow him to transfer money from one bank account to another.