Patton Oswalt says his wife died from a combination of prescription medications and an undiagnosed heart condition

He said in a statement: "We learned the combination of drugs in Michelle's system, along with a condition we were unaware of, proved lethal."

She was taking the medications Adderall, Xanax and Fentanyl and was unaware of her heart condition.

However, despite Patton's statement, the Los Angeles coroner's office insisted the cause of death is still listed as pending.

Michelle - who also left behind the couple's daughter Alice - was the founder of the website True Crime Diary, which covers breaking stories and old unsolved crimes otherwise known as cold cases.

She started the website almost by chance, because she wanted to satisfy her own curiosity of unsolved crimes.

She said previously: "I wanted to get more involved in the cases that were fuelling my own curiosity.

"It's the ones that really don't get that much attention that interest me because I think what's interesting about them is there's more stuff to be unearthed that hasn't been in the public yet and you can do it."

Meanwhile, last year, Patton said getting back to stand-up comedy and sharing his grief with the audience was helping him to cope with his wife's death.

He said: "I think it's a way for me to - it feels like you've summoned this virus and you've become this avatar of loss - to de-summon it the more you talk openly about what it is and put more light onto it, people can see all the angles and say, 'Oh, okay. That is horrible, but there's life on either side of it and it's somehow manageable.'"