HUALIEN, Taiwan — Two days after Taiwan’s deadliest rail disaster in decades, investigators have been working on Sunday to find out why a truck had slipped downhill from a development web site into the trail of an specific practice, ensuing in the collision and derailment that killed dozens of individuals.

The operator of the crane truck, Lee Yi-hsiang, was ordered detained on Sunday by a choose, who reversed an earlier choice to grant him bail. Mr. Lee, who has not been charged with against the law, instructed reporters he had brought on the crash and mentioned he would take full duty for it.

“I hereby express my deep regret and my sincerest apologies,” Mr. Lee mentioned, his voice choking as he bowed in apology.

But investigators have been nonetheless making an attempt to find out whether or not Mr. Lee had uncared for to make use of the emergency brake, or if the truck had malfunctioned in a way. Mr. Lee instructed reporters on Saturday that he had engaged the brake.

Other features of the catastrophe have been additionally being investigated. Officials mentioned they have been making an attempt to find out precisely when the driving force of the practice utilized the brake earlier than the collision.

Officials mentioned on Sunday that 50 individuals had been killed in the crash of the eight-car Taroko Express, which derailed and slammed right into a tunnel wall after hitting the truck on Friday. The practice was packed, carrying 498 individuals on the primary day of an extended vacation weekend.

The authorities had beforehand put the dying toll at 51. Identifying victims has been a gradual and tough course of, and emergency personnel have been nonetheless making an attempt on Sunday to extricate wreckage from the tunnel and recuperate the stays of victims. Thirty-seven survivors of the crash have been nonetheless hospitalized on Sunday, officers mentioned.

Some survivors and relatives of the dead have proven extra grief than anger. Taiwan’s final critical practice crash, in 2018, was discovered to have been caused by driver’s negligence, however preliminary impressions have been that the collision on Friday was one thing extra like a freak accident.

Some members of the family mentioned they didn’t need to assign duty for the catastrophe earlier than the federal government had completed its investigation, which the authorities mentioned would take about two months.

“I don’t want to blame anyone,” Wu Ming-yu, 68, mentioned on Sunday, as she sat with members of the family beneath a tent at a funeral residence in Hualien, a metropolis south of the crash web site on Taiwan’s east coast. They have been ready for a mortuary make-up artist to complete work on the physique of Ms. Wu’s daughter, Huang Chiao-ling, a 35-year-old nurse who had been on her approach to see her household.

Still, Ms. Wu mentioned she was involved that the development web site might have fallen wanting security requirements. “You have to ensure the safety of the construction, because if you don’t you will end up hurting other people,” mentioned Ms. Wu.

The development mission had been commissioned by Taiwan’s transportation ministry to enhance the protection of the slope close to the crash web site, which occurred on a steep mountainside on the Pacific coast. It was half of a bigger, six-year plan to reinforce railway security in Taiwan. Mr. Lee, the operator of the crane truck, was additionally the mission’s web site supervisor.

“It’s ironic and very unfortunate,” mentioned Yusin Lee, a professor of civil engineering and director of the Center for Railway Studies at National Cheng Kung University in the southern metropolis of Tainan. “It’s a reminder that even when we have safety-targeted construction projects, we still have to keep safety in mind.”

At a information convention on Sunday, officers mentioned that Lee Yi-hsiang might have hid a part of his background when he utilized to be the mission’s web site supervisor.

Su Chih-wu, a high quality management engineer on the positioning, mentioned by phone that employees had almost completed the mission, which was targeted on reinforcing the construction of a practice tunnel operating parallel to the one the place the crash occurred.

He additionally mentioned that there mustn’t have been employees on the web site on Friday, because it was the primary day of an extended vacation weekend. It was not clear on Sunday whether or not Lee Yi-hsiang or anybody else had been on the web site that day.

Another engineer on the mission, Yang Chin-lang, rejected the concept that his workforce had failed to make sure an ample stage of security. “I didn’t do anything wrong,” he mentioned by phone. Both Mr. Yang and Mr. Su mentioned that they had been interviewed by prosecutors on Saturday.

“I just followed the design blueprints and did my job,” Mr. Yang added.

The crash occurred close to Qingshui Cliff, an space the place mountains rise dramatically from the Pacific Ocean. Experts say the tough terrain has lengthy offered a problem to transportation engineers, and plenty of accidents have occurred on the winding freeway there through the years. But the rail and freeway routes are a necessary hyperlink between Taipei, the capital, and the east coast.

Feng Hui Sheng, deputy director of the Taiwan Railways Administration, mentioned in an interview on Sunday that the company had made continuous security enhancements to its programs and gear for the reason that 2018 crash.

He mentioned that these modifications would proceed and that the authorities would additionally search to enhance the community’s sign and alarm programs and improve monitor security. But he additionally acknowledged that broader modifications may occur slowly.

“When it comes to the innovation and reform of the system,” he added, “we are more conservative.”

Joy Dong reported from Hong Kong.