Lawyers and activists have questioned the impartiality of the investigations into the killings, which were conducted in the days following the uprising by Mubarak-era officials who still held their posts and by police officers embittered by the protests. The multiple acquittals have fueled calls for reforming the judiciary, which is still made up of judges appointed under Mubarak.
Morsi has promised to hold new trials on new evidence and appointed a new fact-finding mission to investigate the deaths of protests.
Ahmed Ragheb, a human rights lawyer who is participating in the fact-finding mission, said Wednesday's verdict was not a surprise, considering numerous flaws in the procedures leading up to the trial and reported pressures on witnesses and investigating judges from ex-regime officials.
"The acquittal doesn't mean this didn't happen or that so and so did not commit the crime. It means the evidence is not enough," he said. "This is the case in most of the other trials concerning the killing of protesters, because the police, who are accused in the killings, are the ones collecting evidence."
Ragheb said the fact-finding mission has collected new evidence, but that anything short of an overhaul of the judicial system would not mete out justice for the protesters.
"The current judicial system is not qualified to try the state. It is part of it," he said. "We need a new justice system that can protect the revolution," and implement a system of transitional justice to bring former regime officials to trial.
Chief among the defendants in the "Camel Battle" trial was Safwat el-Sherif, one of Mubarak's most trusted aids and secretary-general of Mubarak's National Democratic Party, and Fathi Sorour, who served for decades as speaker of parliament.
Last year, a government-appointed commission investigating the Feb. 2 events released findings, based on testimony from 87 witnesses. The commission said el-Sherif masterminded the attack, making phone calls to ruling party lawmakers and their supporters and telling them to "curb anti-Mubarak protests in Tahrir Square with violence."
"The eyewitnesses said that there was a specific assignment to clear the square by any means," the report said.
Sorour paid thugs anywhere from 50 to 500 Egyptian pounds ($9 to $90) and provided them with meals and drugs to attack the crowd, the commission said.
Witnesses told the investigators they saw ruling party members among the assailants, inciting them against the protesters, and even some on the camels and horses, the report said. "Snipers also took positions on rooftops of residential buildings overlooking the square and they opened fire at protesters."