SINGAPORE — Pointing out that there were holes in the prosecution’s evidence and that investigation processes were not exhaustive, a judge yesterday acquitted SMRT bus driver Zhang Kun of causing a passenger’s death and hurting another passenger.

District Judge Michelle Yap said, for instance, that the inspection of the bus involved in the accident was not thorough enough, and the bus had been released prematurely to SMRT. She also said that the speed data retrieved from the black box of the bus appeared to be inaccurate at times.

Zhang, 43, a Chinese national, was charged with causing the death of a passenger and injuring another by a rash act on July 21, 2013, when he was driving bus service 700A.

At around 9am, he allegedly drove above the speed limit of 50kmh along a slip road leading from Bukit Timah Expressway to Dairy Farm Road.

He lost control of the bus, and it veered across the road to the centre divider and hit a concrete barrier before overturning.

Sasikumar Gunasakaran, a Malaysian who was 19 at the time, was found crushed between seats, and his body had to be extricated by rescue workers. Mr Ramanand Panday, another passenger, was injured.

Zhang’s lawyer, Anil Balchandani, argued previously during the trial that the bus had two mechanical faults: Poor brakes and an engine that accelerated on its own. However, the defence did not have the chance to inspect the bus in its original state because it was returned to SMRT and partially dismantled even before Zhang was charged in court.

District Judge Yap said, “I am of the judgment that the Investigative Officer in this case had wrongfully released the accident bus to SMRT. Consequently, the accused was unable to conduct its own inspection of the vehicle to determine if there was any mechanical fault.”

Prosecution witness Tan Jiat Shee, from vehicle inspection centre STA, carried out a brake-efficiency test on a similar bus and found that there were no mechanical faults with the bus in the accident. He claimed that he could not conduct the test on the accident bus, because its engine was seized as a result of the crash.

However, the judge pointed out that there was a “vast disparity” in the condition of the two buses, such as their mileage and maintenance. Beyond that, it later emerged that SMRT personnel managed to carry out the test on the accident bus and that was “most troubling”, she added.

“It is strange, therefore, why Mr Tan had insisted that brake efficiency tests could not have been conducted on the accident bus itself, and that no such tests were in fact conducted,” District Judge Yap said, pointing out that his inspection could not rule out other possible mechanical faults.

Mr Tan claimed that he had controlled access to the accident bus at all times, but the possibility that SMRT staff members had unsupervised access to the accident bus meant that “there was a break in the chain of custody over crucial evidence”, she said.

“This is important because SMRT is an interested party to the case,” she added.

As for the speed data retrieved from the black box, despite the prosecution claiming that the steepness of the slip road had caused the bus to accelerate from 56kmh to 78kmh, there was no evidence to show how the gradient of the road could have affected the speed, the judge said.

Furthermore, there were speed-regulating stripes on the road, and Zhang had stepped on the brakes along the slip road.