Human rights NGO Suaram has criticised deputy public prosecutors in an extra-judicial killing case for allegedly being ill-prepared and causing delays.

The Shah Alam High Court was to decide on the application for a second post-mortem for Mohammad Shahril Sugumaran Abdullah after hearing the prosecution's dissenting arguments.

Police said Mohammad Shahril and S Uvarajan were killed in a shootout in August, but their family is seeking a second post-mortem given the wounds on the remains.

However, the remains of S Uvarajan have been cremated while Mohammad Shahril's remains have to be exhumed.

Citing the families' lawyer V Visvanathan, Suaram executive director Sevan Doraisamy said the deputy prosecutor was not prepared to deliver the dissenting arguments, so the case was postponed to Oct 28.

"This delay could affect evidence and ability to mete out justice for the victims in a timely manner.

"Suaram believes that justice delayed is justice denied," he said in a statement.

The two were killed along the Selayang-Kepong Expressway in the wee hours on Aug 19.

Selangor police criminal investigation head Mohd Adnan Abdullah had said the incident occurred after police noticed a car being driven in a suspicious manner.

The police gave chase after the driver attempted to crash through a roadblock.

The two suspects then allegedly fired at the police, leading the police to return fire, resulting in their deaths.

Mohd Adnan said police believed the suspects were involved in four murder cases reported in the Klang Valley.

Uvarajan’s brother, S Devendran, however, said he was told by an officer at the Gombak police district headquarters that his brother was only involved in one case – a fight.

Devendran also questioned the other wounds, such as handcuff marks, found on his brother’s body.