Metropolitan Police Bureau (MPB) chief Charnthep Sesawech has ordered the formation of a panel to revisit a case in which a 23-year-old man was stabbed to death two years ago.

The panel was ordered after the man's father plunged to his death on Monday following the lower court's ruling to dismiss the murder case.

MPB deputy chief Sompong Shingduang said on Thursday that he'd been ordered by Pol Lt Gen Charnthep to establish a committee to probe the case. He said officers will examine whether the past investigation had flaws and the court's ruling was being copied for deliberation. However, he conceded it would be difficult to revive the case if no new evidence is found.

The case has been through the Court of the First Instance's deliberation and there are still Appeal and Supreme Courts to pursue, Pol Maj Gen Sompong said.

Thanit Thalahasunthon was stabbed to death during the Songkran festival on April 15, 2016. The Criminal Court on Monday dismissed a criminal suit filed against Nattapong Ngenkiri, 19.

Following the ruling, Thanit's father, Supachai Thalahasunthon, who was a co-plaintiff in the case, jumped to his death from the 8th floor of the Criminal Court building.

Responding to reports that the acquitted suspect may have been assisted by police as he allegedly knows influential figures, Pol Maj Gen Sompong said an investigation is underway to determine whether such allegations carry weight.

As for complaints raised by Supachai's relatives that the man was told by investigators to look for evidence in the case by himself, Pol Maj Gen Sompong said he was not aware of that information and the investigation will be carried out to ascertain whether the officers involved had misbehaved.

He insisted he does not feel pressure to revisit the case since it depends on the evidence. If evidence cannot be used or none is found, it would be impossible for officers to fabricate it. If it is found that evidence already existed but officers failed to use it, they could face charges for negligence of duty, he said.

The team of investigators previously probing the case has been called to meet the MPB chief for questioning, though the time schedule has yet to be settled, Pol Maj Gen Sompong added.

Pol Lt Gen Charnthep said the widow of Supachai, Rewadee, had submitted all documents related to the case compiled by her late husband to officers, who will restart compiling evidence which can be used during the hearing in the Appeal Court.

The officers will also look into prosecutors' instructions given to police to determine which evidence should be sought, he said.

Deputy Prime Minister and Justice Minister Prajin Juntong said relevant agencies would be asked to attend a meeting either on July 31 or Aug 1 to discuss the case.