A Taiwan court on Saturday released on bond the manager of a construction site whose truck authorities believe caused a train accident that killed at least 51 people, as family members mourned the dead at the crash site.

The crash on Friday was Taiwan’s worst rail accident in seven decades, when an express train hit the truck that had slid down a bank beside the track from the building site. The site’s manager is suspected of having failed to properly engage the truck’s brake.

The train, with almost 500 people aboard, was travelling from Taipei, the capital, to Taitung on the east coast when it derailed in a tunnel just north of the city of Hualien. Forty one people are in hospital, from among the 188 reported injured.

Prosecutors had applied to a court to detain the manager on charges of causing death by negligence, a justice ministry official told reporters on Saturday.

But a court in Hualien released the manager, Lee Yi-hsiang, on a bond of T$500,000 ($17,525), although it restricted him from leaving Taiwan for eight months and said he had to stay in Hualien.

The court said that while the truck’s fall into the path of the train was possibly due to negligence, there was “no possibility of conspiracy”.

Yu Hsiu-duan, head of the Hualien prosecutors’ office, said they were not pleased with the decision. “The court said there was no reason to keep him in custody,” she told reporters.