The draw provoked uproar after the number 21 was shown on screen instead of the ball the lotto machine dropped – 27. The ball for 21 was drawn next.
Nobody claimed the one million euro (US$ 1.1 million) jackpot that evening.
The lottery is a shot at a more prosperous life for many in the Balkan state, which is hindered by high levels of unemployment and corruption.
According to Serbian national television (RTS), police questioned a number of people involved in the lotto draw on Thursday, including members of the lotto's monitoring commission, technical staff and the host of the TV show.
Interior Minister Nebojsa Stefanovic said that those questioned had been given lie detector tests, which were then forwarded to the state prosecutor.
He said computer equipment, including machines holding ticket sales data, had been confiscated and would be examined by experts, along with the balls showing the lotto numbers.
Aleksander Vulovic, director of the state lottery, maintained the legitimacy of the draw at a Wednesday press conference. He claimed there was no existing device that could influence which numbers would be drawn from the lotto machine.
The next day he resigned, citing "moral reasons", according to RTS.
The president of the commission that monitors the lotto draw told journalists that the person charged with entering the numbers for the screen display as they came out of the machine had simply mistyped. He claimed that the odds of such a coincidence were not outlandish, drawing laughter from the assembled crowd.
As the scandal dominated Serbian airwaves and headlines, Prime Minister Aleksandar Vucic weighed in to reassure the public that, should investigators find any irregularities, those reponsible would face justice.
Despite the scandal, Radio Television Vojvodina (RTV) reports that the state lottery told them of an increase in ticket sales the day after the controversial draw, suggesting it had not lost credibility.
When RTV reporters questioned people if they trust the state lottery on the street, however, they got a slightly different picture.
"I played [the lottery] until now, but I have stopped... it is a scam," said a woman questioned by RTV.
