A toxicology report showed that Dunn's blood-alcohol content was more than twice the legal limit for drivers.
Dunn and a passenger, identified as Zachary Hartwell, died in a fiery one-car crash early Monday morning. Police said Dunn was speeding and may have been going as fast as 140 mph when his Porsche veered off the roadway, went airborne and crashed into the woods in a Philadelphia suburb.
The Chester County coroner listed blunt force trauma and thermal trauma as the official causes of death for both men.
A few hours before the 3 a.m. crash, Dunn tweeted a picture of himself drinking with Hartwell and another friend. The photo has since been removed.
Movie critic Roger Ebert was under fire over his controversial Twitter message regarding Dunn's death. Referring to the photo of Dunn drinking with friends just hours before the accident, Ebert tweeted: "Friends don't let jackasses drink and drive."
The tweet prompted a landslide of Twitter messages and Facebook posts, some profane, criticizing Ebert.
Ebert later wrote in a Tuesday blog post, that he didn't mean to be cruel and "was probably too quick to tweet. That was unseemly."
The Associated Press contributed to this report.