Samantha Mathis has spoken publicly about River Phoenix for the first time since his death in 1993.

The actors met while working on The Thing Called Love and began a romantic relationship on set.

Speaking to The Guardian, Mathis revealed that she recently watched the 1993 comedy for the first time since Phoenix's death, and, after being approached by the publication, felt “like the universe wanted me to talk about him”.

Phoenix died aged 23 of an overdose of cocaine and heroin on 31 October 1993 outside the Johnny Depp-owned Viper Room nightclub in Los Angeles. The actor's younger sister and brother, Rai and Joaquin, were at the club, along with Mathis.

“I knew something was wrong that night, something I didn’t understand,” Mathis said. “I didn’t see anyone doing drugs but he was high in a way that made me feel uncomfortable — I was in way over my head. Forty-five minutes later, he was dead.”

Mathis says that she went to the bathroom and when she emerged, Phoenix was engaged in a scuffle with another man. After security escorted the group out, Phoenix began to convulse on the ground.

“I knew he was high that night, but the heroin that killed him didn’t happen until he was in the Viper Room. I have my suspicions about what was going on, but I didn’t see anything,” she said.

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Phoenix was a highly-celebrated actor during his lifetime, receiving an Oscar nomination for his role in Sidney Lumet's Running on Empty. Mathis has had a successful career in Hollywood, going on to star in American Psycho, Broken Arrow and Little Women.

Remembering Phoenix, she called him “sensitive and obsessive," adding that he felt things "on his heart very deeply.”

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