Police at the time ruled his death a suicide by hanging, but said they would continue to look into the matter - including whether he'd been under the influence of any substances at the time.
Bourdain was found on June 8 in his hotel bathroom in Kaysersberg, a small village in France.
Celebrity chef Anthony Bourdain did not have any narcotics in his system when he died earlier this month, according to French investigators. The former chef had only a nonnarcotic medication in his system, in a therapeutic dose, the prosecutor reportedly said by text message.
Bourdain had been open about his use of drugs in the past, saying that in the 1980s, he struggled with serious drug problems.
"No trace of narcotics, no trace of any toxic products, no trace of medicines, no trace of alcohol", prosecutor Christian de Rocquigny told Reuters on Friday.
Bourdain was cremated in France last week and his remains were then sent back to his younger brother, Christopher, in the United States.
Ms Bourdain plans on getting a tattoo of the name "Tony" tattooed on the inside of her wrist next week.
CNN confirmed the chef's death: 'It is with extraordinary sadness we can confirm the death of our friend and colleague, Anthony Bourdain.
Bourdain first gained global fame after penning the 2000 book Kitchen Confidential: Adventures in the Culinary Underbelly.
Asia Argento is paying tribute to her late boyfriend Anthony Bourdain by sharing a new selfie of them together.
Bourdain had his own TV show on CNN called, Parts Unknown, where he traveled around the world and tasted and created various cuisines. He was 61 years old.