A year after security forces opened fire on a protest at the Kbal Thnal bridge in Phnom Penh, killing 29-year-old Mao Sok Chan, the last suspect charged for taking part in what the authorities said was a violent protest has been released.

Nguyen Thydoc was released shortly before 11am yesterday morning after spending a year in Prey Sar prison, his lawyer said.

He was found guilty of intentional violence and intentional destruction of property, along with two others arrested during the clash on September 15, 2013, and given a three-year sentence with two years suspended.

Van Neun and Lach Sameun were also sentenced to three years in February but were let go with time served.

Sam Sokunthea, a lawyer from rights group Licadho who is representing Thydoc, said his client continued to seek an appeal hearing in his case.

“Since the judge read out the verdict, we have appealed the decision, but until now, the appeal court did not schedule a hearing,” he said.

Sokunthea added that Thydoc had gone to visit his grandmother after his release.

Nguyen Thysaw, Thydoc’s 67-year-old grandmother, spoke yesterday of her joy at seeing him again.

“I cried almost every day during the year that I waited for my grandson to get out of jail. Sometimes I thought I would die before I saw him again.”

The anniversary of the shootings and Thydoc’s release prompted questions over the progress of an investigation into authorities’ use of force that the government said it had launched after Sok Chan’s death.

“We don’t know how much evidence they collected . . . we don’t know who is the investigating judge . . . We have not heard if they interviewed any witnesses,” legal expert Sok Sam Oeun said.

Ou Virak, chairman of the Cambodian Centee for Human Rights, said the “investigation” had never existed.