Williams, 27, pleaded not guilty in the case and put his fate in the hands of a jury, which was likely to get the case today.
Shortly after Venziale testified, the government and defense rested. Neither Williams' attorney, Joseph Valvo, nor the attorney for co-defendant and reputed drug dealer Zachary Young, Anna Durbin, put up any witnesses.
Closing arguments were set for this morning.
Venziale calmly told jurors that on May 14, he and Williams pulled up behind a car with their cruiser's strobe lights on and sirens wailing. At the time, both were on duty and in uniform.
Venziale testified about how he and Williams staged a fake arrest of a passenger in the car, admitted drug dealer Angel Ortiz, and later released him.
Venziale said that that evening, the two officers, who were still on duty and in uniform, met up with Ortiz and a man whom they believed was a money launderer named Matt McCue, but who was really an undercover DEA agent.
Williams got out of the cruiser, spoke briefly with McCue and then "got back in the patrol car with a bag of money," Venziale said.
Venziale said the officers looked in the bag, found $6,000 in cash and split it 50/50.
Venziale testified that he initially got involved in the plot after discussing it with childhood friend and fellow police officer Robert Snyder, who pleaded guilty last month to drug conspiracy.
It was Ortiz's idea to use cops in a staged traffic stop and drug heist, Venziale said. He said that he later broached the idea with Williams and that Williams told him he was "interested."
Both officers subsequently joined the plot but were "skeptical" of McCue, whom they thought might be an "undercover cop," Venziale said.
So Snyder and Williams checked out McCue, Venziale said, adding that Williams ran the tag number of McCue's vehicle through a computer in their cruiser.
Venziale also implicated Williams in the planned robbery last July of somebody who was purported to be a mafioso with gambling proceeds but who was really an undercover FBI agent.
On cross-examination, Valvo lit into Venziale, accusing him of "throwing [Mark] Williams under the bus" so that he might get a break at sentencing.