Authorities said no suicide notes or other clues were found to reveal the last, private moments of a very public life that ended last Wednesday in a secluded, three-room apartment in rural Solebury Township, near New Hope.
Hoffman, 52, died alone in bed, where his landlord and a neighbor found him several hours later at 8:15 p.m., fully dressed and curled in a fetal position.
"I believe he went to sleep, fell into a coma and stopped breathing," Rosko said. He said Hoffman probably died "several hours" after taking the drugs.
The coroner said he had no idea why Hoffman may have killed himself, but friends and family have said the confrontational radical was a manic- depressive who had periods of severe depression.
Even so, Hoffman's brother, Jack, was adamant yesterday in his refusal to believe Abbie would have gone without a word, at a time when their elderly mother, Florence, 83, was suffering from a recurrence of lymphatic cancer.
"I won't believe it. No. It's important what I believe," Jack Hoffman said in a telephone interview, his voice muffled with exhaustion.
"He never disappointed me," Hoffman said. "There was always a method to the madness somewhere along the line."
More than four grams of phenobarbital - an amount equal to 150 30-milligram pills - was found in Hoffman's stomach during an autopsy last week, Rosko said. Subsequent toxicology tests revealed additional amounts of the barbiturate in Hoffman's bloodstream, as well as a blood alcohol level of 0.20 - double the legal level for intoxication.
"The evidence is that (the phenobarbital) was taken pretty much all at once," Rosko said.
It was unclear whether Hoffman had a prescription for phenobarbital, but Rosko said no empty prescription bottles for the drug were found during searches of the apartment.
Jack Hoffman said his brother took numerous medications and that he was ''experimenting" with alternative treatments for his manic-depression. But Hoffman said he had never known his brother to take phenobarbital.
"That strikes me as being a very strange pill (to be) around there," he said.
During Rosko's news conference, the coroner declined to comment when asked about substances that appeared to be small quantities of illegal drugs that had been recovered from Hoffman's apartment. He said that no traces of illegal drugs had been found in Hoffman's system but that tests to measure small amounts of such substances had not been completed.
Two other prescription medications - a cardiovascular drug and an anti- anxiety drug similar to valium - were found in Hoffman's body but did not contribute to his death, Rosko said.
Johanna Lawrenson, Hoffman's common-law wife, yesterday left the Solebury property with Hoffman's landlord, Michael Waldron, to drive to Massachusetts, where a family memorial service was planned for today in Worcester.
A peace march was scheduled to begin at noon at the the house where Hoffman's mother lives. The march, to be led by folksinger Pete Seeger, was to end at his childhood synagogue, where a memorial service was to be held.
Plans are being made for a major memorial event May 7 in Central Park in New York City, according to Jack Hoffman.
Hoffman said yesterday that his brother's controversial life led him to take many risks and earned him some powerful enemies.
"He played with death a lot. Look who he was. There was always someone around the corner," Jack Hoffman said.
"It's not a simple suicide in my mind, in my heart, in my head," he said. ''There are too many unanswered questions."
Responding to Hoffman's comments, Bucks County District Attorney Alan M. Rubenstein said all his questions about the death have been answered.
"This is clearly a suicide," Rubenstein said. "Mr. Hoffman is talking
from the heart. . . . No one likes to face the fact that their relative has committed suicide."
Several of Abbie Hoffman's friends said shortly after his death that they would not be surprised if Hoffman had committed suicide.
"Either it was something very natural or he killed himself. Either one wouldn't surprise me," said William Kunstler, the trial lawyer for Hoffman and others in the Chicago Seven, who were prosecuted for conspiracy to incite violence at the 1968 Democratic National Convention in Chicago.
"You wear out after a while," he said.
Abbie Hoffman roared into the media spotlight more than two decades ago on the wave of social and political upheaval that marked the 1960s.
Hoffman, along with Jerry Rubin and Paul Krassner, started the Yippie movement - Youth International Party - to protest the Vietnam War and other government policies.
One way or another, the man who once said, "Never trust anyone over 30," had managed to keep the public's attention through the years, even as his frizzled hair grayed and his body slumped into the paunch of middle age.
Hoffman spent seven years underground to avoid trial on cocaine-trafficking charges during the 1970s. During that time, he adopted a new name, Barry Freed, and took an active role as an environmentalist working to protect the St. Lawrence Seaway in upstate New York.
Hoffman resurfaced in 1980 and served a two-year prison sentence after pleading guilty to a lesser charge of cocaine possession.
In August, he stood inside the Chicago Amphitheater on the 20th anniversary of the infamous 1968 Democratic Convention and exhorted a crowd of about 300 people to stoke the fires of political activism.
It is possible, however, that Hoffman's own fire already was flickering. He had been in a car accident two months earlier that left him with persistent health problems that continued until his death.