It was tough for Billy Crystal to see his friend’s deteriorating condition; now he is opening up about the days, weeks, and months preceding Robin Williams’ death.

“He wasn’t feeling well but he didn’t let on to me all that was going on,” Crystal said in a Vanity Fair excerpt from the new biography Robin. “As he would say to me, ‘I’m a little crispy.’ I didn’t know what was happening, except he wasn’t happy.”

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Crystal recalled one particular encounter with Williams in 2013. “I hadn’t seen him in about four or five months at the time, and when he got out of the car I was a little taken aback by how he looked,” he told author Dave Itzkoff. “He was thinner and he seemed a little frail.

“He seemed quiet. On occasion, he’d just reach out and hold my shoulder and look at me like he wanted to say something,” he continued. “He hugged me goodbye, and Janice and he started crying. I said, ‘What’s the matter?’ He said, ‘Oh, I’m just so happy to see you. It’s been too long. You know I love you.'”

Crystal, 70, and Williams have shared the screen multiple times, co-starring in movies like “Father’s Day”, “Get Bruce”, and “Hamlet”.

“His number comes up on my phone and he says, ‘Hey, Bill.’ His voice was high-pitched,” Crystal remembered. “‘I’ve just been diagnosed with Parkinson’s,’ Williams revealed to him. “I didn’t miss a beat. Because of my relationship with Muhammad Ali, I knew a lot of really good Parkinson’s research doctors.”

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“I said, ‘In Phoenix, the research centre is great. If you want, we can get you in there. It would be totally anonymous. Do you want me to pursue that?’ Would you?’ I never heard him afraid like that before,” continued Crystal. “This was the boldest comedian I ever met — the boldest artist I ever met. But this was just a scared man.”

Williams passed away on Aug. 11, 2014, at the age of 63.