POLICE YESTERDAY struggled to identify suspects behind the bombing at Phramongkutklao Hospital on Monday even as Prime Minister Prayut Chan-o-cha insisted the “bad guys” would be arrested.

However, sources said suspicion pointed to former security officers with close connections to unspecified political factions.

“It happened where it shouldn’t have. There’s no other reason besides those bad guys are still out there,” Prayut said. “We have to get rid of these bad people and it’s time for us to join hands together.”

“We are following the case closely. There are many people involved, as no one could do such a thing alone. Sometimes they just hire a 14-year-old kid for Bt200 to do the job,” Prayut told reporters, but he added that he did not know who had carried out the bombing.

However, a source close to investigation said a five to six-member group, also involved in the previous two bombings in Bangkok – near the Government Lottery Office and National Theatre – had carried out the attack to discredit the military government.

Police yesterday announced that they had a sketch of one suspect’s appearance and would use it to ask for a court-ordered arrest warrant, according to deputy national police chief Pol General Srivara Ransibrahmanakul.

Police are also trying to identify who sent a warning letter to the National Cancer Institute three days before Phramongkutklao Hospital was attacked.

Deputy Defence Minister General Udomdej Sitabutr said the institute’s director, Dr Weerawut Imsamran, received the letter last Friday and had already filed a complaint with police.

The letter warned of a possible terrorist attack by the southern insurgent group Barisan Revolusi Nasional and the Islamic State, which reportedly would be carried out by a Muslim woman wearing a headscarf and carrying a backpack. The attack was supposed to target three state hospitals in the same area as the institute.

The other nearby hospitals are Ramathibodi Hospital on Rama IV Road as well as Children’s Hospital, Rajavithi Hospital and Phramongkutklao Hospital, all of which are on Rajavithi Road. It was not immediately clear which hospitals were being targeted in the warning.

Meanwhile, police yesterday summoned a person of interest, Awae Yusuf, whose name and address were reportedly written on the envelope of the letter, a source said.

Police did not find anything suspicious after searching Awae’s residence, and he was released later in the day. The source quoted Awae as telling police that he had not sent the latter but he admitted that the address was his.

The handwritten letter was posted from Pathumwan district.

Deputy national police chief Pol General Srivara said authorities had been put on alert at other hospitals, but not at Phramongkutklao Hospital after learning about the warning letter.

Security measures

Weerawut said his institute had intensified security measures following the Phramongkutklao Hospital attack with officials instructed to closely monitor the area for unusual behaviour or suspicious items.

Officials have also been assigned to check the functioning of about 80 security cameras at the hospital’s premises.

Chutima Pulllarb, deputy director of Children’s Hospital, said the hospital had prepared security measures and increased safety precautions following the Monday bombing.

More lights will be installed inside the compound and security cameras checked, while staff will enforce hospital rules concerning garbage cans and tree planters.

Ramathibodi Hospital director Dr Surasak Leelaudomlipi said the facility had prepared security measures to be implemented 24 hours a day. Hospital staff had been ordered to wear badges and they would be subjected to routine checks, he said.

The hospital has 650 security cameras, with staff considering installing more, particularly in corner areas.

Dr Manas Photarom, director of Rajavithi Hospital, said the hospital had strengthened safety measures and instructed officials to help monitor for unusual items and behaviour at the instruction of the Public Health Ministry. There are about 400 security cameras installed at the hospital, Manas said, adding more would be installed particularly in at-risk areas.

The homemade bomb at Phramongkutklao Army Hospital injured 25 people on Monday, the third anniversary of the 2014 coup.

Authorities have stepped up security measures in many areas with about 20 Red Beret Army rangers from the Special Warfare Command standing guard at Government House yesterday.

Soldiers inspected security measures at the compound and checked tall buildings and other locations where potential attacks could be staged.