Journalists were not permitted inside the courtroom, but Rafael Ojeda, an attorney representing Makled, said his client was present along with eight other suspects when deliberations began.
Makled was captured in Colombia in 2010 and extradited to Venezuela last year. While under arrest in Colombia, he caused a stir when he told a television channel that he made monthly million dollar payments to a group of more than 40 military officers in Venezuela.
President Hugo Chavez has dismissed Makled's allegations involving purported ties to his government and the military as false.
Both Venezuela and the United States had requested Makled's extradition. Colombian President Juan Manuel Santos decided to turn him over to Venezuela, saying Caracas made its request first.
Makled is accused in the killings of Venezuelan journalist Orel Sambrano and a veterinarian, Francisco Larrazabal. Authorities say Larrazabal witnessed a 2008 drug raid at the Makled family ranch in which nearly 880 pounds (400 kilograms) of cocaine was seized.
Makled denies any wrongdoing.
One of his employees, Luis Jose Gonzalez, was sentenced to 11 years and six months in prison after pleading guilty to drug trafficking charges linked to the 2008 seizure at the ranch, according to a statement released by the Prosecutor General's Office on Monday.
Opponents of Chavez lamented that the trial was closed to the news media and opposition politicians.
"The trial has gotten off ... to a bad start," anti-Chavez lawmaker Miguel Angel Rodriguez said. "We regret they are putting up obstacles to enter."
Rodriguez said transparency in the trial would "dispel the perception that Venezuelans have regarding the ties that operations controlled by Walid Makled could have had."
Makled's bothers, Abdala, Alex and Basel, are facing drug smuggling and money laundering charges.