A close friend of Janis Joplin said the singer didn't die by an overdose, and offered her theory as to what happened.

Joplin was found dead on the floor of her Hollywood hotel room in October 1970, and the death was ruled to be accidental. It was widely thought she’d died as a result of extremely strong heroin, an idea supported by the fact that several of the same drug dealer’s customers also overdosed in the same week.

In a new book, Joplin’s friend Peggy Caserta questioned that version of events, and said that a detail she’d seen in the room had always concerned her, and suggested that, after having taken heroin, Joplin appeared to have visited a cigarette vending machine in the lobby.

Writing in her recently published memoir I Ran Into Some Trouble (via Rolling Stone), Caserta said, “I saw her foot sticking out at the end of the bed. She was lying with cigarettes in one hand and change in the other. For years it bothered me. How could she have overdosed and then walked out to the lobby and walked back? I’ve overdosed, and you crumble on the floor like how they found Philip Seymour Hoffman. I let it go for years, but I always thought, ‘Something is wrong here.’”

She said her opinion was reinforced by the fact that she’d taken some of the same supply of heroin. Her own take on the tragedy was that Joplin, who was wearing sandals with a “tiny hourglass heel,” had tripped on the room’s deep shag carpet, fallen and broken her nose, which led her to asphyxiate.

Caserta’s book is intended, in part, to address inaccuracies in 1973 book Going Down With Janis, which contains details of the pair’s intimate relationship. “I didn’t write that smut about Janis,” she said. “I would never talk like that about our close association. But I lost control because I was strung out and making awful decisions.”

She reflected of her death theory, “Does it matter at this late date? In some ways maybe it doesn’t. But what matters is the truth, and the truth is that she didn’t overdose. I will go to my grave believing that. God knows I’ve been there several times.”