Traces of strychnine were discovered in three bottles of Extra-Strength Tylenol for sale in California after a 27-year-old man became violently, but temporarily, ill last Thursday, the Food and Drug Administration reported yesterday.

The new development in the spreading mystery immediately caused the manufacturer of the drug to ask stores to halt all sales of Extra- and Regular-Strength capsules nationwide. The company stopped producing both forms of Tylenol capsules Friday.

It was the first reported case of apparent poisoning involving Tylenol outside the Chicago area, where seven died last week after swallowing capsules containing cyanide.

Last night, however, the body of a truck driver found slumped over the steering wheel of his rig in Tennessee was sent to Memphis for an autopsy because authorities found three foil-wrapped Tylenol capsules in the seat beside him.

District Attorney Jim Horner of Dyersburg said the body of Thomas Isbell, 46, of Kenton, Tenn., was found yesterday in his truck at Tiptonville. The autopsy is scheduled for this morning.

About the California incident, an official of McNeil Consumer Products of Chicago, which manufactures Tylenol, said there is "no reason at this time to believe that there is a relationship between the California and Chicago cases.

A spokesman for the FDA said the agency's Philadelphia laboratory had "independently confirmed" that capsules from two bottles taken from an Oroville, Calif., pharmacy contained strychnine, a substance frequently used to poison rats and predators. It also is used medically, in small quantities.

"The bottles appear to have been tampered with. . . . You can see pink flecks. It's a sub-lethal dose, enough to make you sick, but not enough to kill you," said William C. Hill of the FDA's San Francisco office.

The victim of the apparent poisoning was Gregory Blagg, an Oroville butcher, who told a news conference last night in a parking lot outside his lawyer's office that he had taken two Tylenol capsules about 3:30 p.m. Thursday after suffering headaches. About 5 p.m., he said, he lost consciousness briefly in his home and went to the hospital.

Doctors "concluded my problem was nervous anxiety," he said. After taking medication he was released and returned home in time to see television reports about the Tylenol deaths in Chicago.

Blagg said his wife, Terry, had purchased the Tylenol bottle about two or three weeks before he took the medication. He said he opened some of the capsules after seeing the news report and found small pink granules among white granules.

The next day he visited Dr. John P. Clay, a physician who examined the pink capsules and checked with a pharmacist to make sure the material inside the capsule should be white. Blagg said he then contacted attorney Joseph Vandervoort, who told the pharmacy about the capsules.

"The doctor asked me what color the powder in Tylenol capsules should be, and I told him white," said pharmacist Frank Dayton, who was reached by telephone. "Then he said the powder he had was pink."

Analysis of the capsules' contents during the last three days by McNeil and, independently, by the FDA, confirmed that the capsules contained strychnine.

At the same time, an FDA spokesman in Washington said that a third bottle, taken from Long's Drug Store, where the first two bottles allegedly were purchased, also showed traces of strychnine.

Neither government or company officials yesterday could explain why there had been a three-day lag between the initial suspicions about the capsules in Oroville and yesterday's announcement by McNeil.

Although company officials said they did not believe the two incidents were connected, the timing of the California incident appeared to rule out the possibility that it was the work of a criminal imitator.

Publicity about the Tylenol deaths in Chicago did not begin until late Thursday. But the Tylenol taken by Blagg apparently was purchased before the nationwide publicity.

The three tainted bottles from Oroville were from a lot numbered 1766MA, a batch that had not been implicated in the Chicago cyanide poisonings.

Even as these clues were being evaluated by medical investigators, a hastily assembled task force of specialists from the over-the-counter drug industry and the FDA was considering ways to prevent similar incidents in the future. But members of the group acknowledged that there are limits to the security that can be provided.

Even after the publicity concerning the Tylenol poisonings, some users of the drug have continued to demand it from their pharmacies, and law enforcement officials in Chicago say that an under-the-counter black market in the drug has developed in that city, where Tylenol capsules have been withdrawn from sale.

Illinois Attorney General Tyrone Fahner said yesterday, "We have no reason to suspect there is any connection" with the Chicago cyanide cases. "But caution precludes me from saying there is no connection."

He told an evening news conference that his investigation has narrowed to "eight or nine" suspects, all Chicago-area residents. He said none had been in California during the period in question.

Fahner said that not all of the primary suspects have been interviewed and that "it looks less and less that it's more than one" person involved.

He said another dozen officers would be added to the 100-member task force probing the murders in the Chicago area.

A federal law enforcement source, who declined to be identified, told the Associated Press that investigators had not discounted a possible link between the California and Chicago cases.

Chicago police also are studying a link between the murders and hundreds of Extra-Strength Tylenol capsules dumped in a motel parking lot.

Those capsules were found by two sheriff's deputies the day before the first deaths. Fahner said lab tests so far show no trace of cyanide in those capsules. But Fahner said this doesn't rule out a link.

"We still don't know why somebody would throw all those pills in a parking lot," Fahner said.

The Tylenol tragedy also has begun to have international repercussions.

The Philippines ordered a recall of all Extra-Strength capsules Tuesday. Britain has posted signs warning tourists of possible dangers from the drug. U.S. Army post exchanges have been ordered to remove all Tylenol capsules from the shelves, and Italian state television has issued a nationwide warning that the capsules could be dangerous.