In a bizarre phone call from the U.S. jail where he’s serving four years for the manslaughter of Michael Jackson, the king of pop’s former doctor Conrad Murray serenaded CNN’s Anderson Cooper Tuesday night. 

Murray unexpectedly sang Nat King Cole’s ‘The little boy that Santa Claus forgot,’ during a live interview on Cooper’s CNN talk show.

Murray began singing after Cooper brought up the topic of the Jackson family’s wrongful death lawsuit seeking billions of dollars in damages from concert promoter AEG Live. Asked if he would testify on behalf of the family, Murray said Jackson would be upset to see what has unfolded since his death.

Murray added that he, too, “experienced pain†like Jackson did. Then he broke into song

The song’s lyrics include: "He is a little boy that Santa Claus forgot and goodness knows he did not want a lot. He wrote a note to Santa for some crayons and a toy, it broke his little heart when he found Santa hadn't come in the streets. He envied all the lucky boys, but goodness knows he didn't want a lot. I'm so sorry for that laddie who hasn't got a daddy. He's a little boy that Santa Claus forgot.â€

“That song tells my story, that’s how I grew up,†Murray explained as Cooper appeared visibly perplexed. “I had no Christmases, I had no toys. I had nothing… but as I grew up, my heart has been whole and my heart says to help. And all I do is give.â€

In November, 2011, Murray was found guilty of administering the fatal dose of Propofol which claimed the King of Pop’s life two years earlier.

Murray, who has maintained his innocence since Jackson died, told Cooper the singer’s death represents an overwhelming loss.

Asked if he felt guilty about the death, Murray said: “I’m an innocent man, Anderson. I maintain that innocence.

“I must tell you I’m extremely sorry that Michael has passed on. It’s a tremendous loss for me. It’s a burden I’ve carried for the longest while and it’s a burden I will carry for an indefinite period of time.â€

Murray’s live chat with Cooper is one of two he granted CNN. The other was an interview with Don Lemon recorded last Friday. This is the first time he has spoken to journalists, on the record, since he was convicted in 2011.