The results of the autopsy, released on Sunday, showed that Belgacem had 0.93 grammes of alcohol in his bloodstream, twice the legal limit for a driver, as well as evidence of drug-taking.
A few grammes of cocaine and a machete were found at his flat after he was killed when he attacked soldiers at the Paris airport on Saturday morning.
Although he shouted that he was "ready to die for Allah" during the attack and had been investigated for links to radical Islam, his father told French radio on Sunday that his son did not pray, drank and took drugs and was "not a terrorist".
Belgacem, who was on probation following a six-month jail term for housebreaking, started his rampage when he fired on a traffic police checkpoint, slightly injuring one officer.
He went on to fire a pellet gun in a bar he used to frequent, steal a car and stage the Orly attack.
His father, brother and cousin, all of whom went to the police of their own accord, were released on Sunday after questioning.
No to security checks at airport entries
- A total of 7,000 people are employed in security at Paris's Charles De Gaulle, Orly and Le Bourget airports;
- 66 million people pass through Charles De Gaulle airport every year, 30 million through Orly;
- 16 people were killed in an attack at Brussels's Zaventem airport in March 2016;
- 47 people were killed in a triple suicide attack at Istanbul's Ataturk airport in June 2016.
The attack has revived the debate on security and France's state of emergency ahead of France's presidential election in April and May this year.
Paris airports boss Augustin de Romanet on Monday opposed the idea of extra security checks at the entrances of airports or on roads leading to them.
Conceding that Belgacem had not been searched, he pointed out that more checks would lead to more queues, which would be potential targets for attacks.
There should be "extremely effective" security measures, however, he said, advocating facial-recognition cameras that could identify "anybody suspected of being dangerous".