Police are confident they arrested the right man for the bombing of Phramongkutklao Hospital, Defence Minister Prawit Wongsuwon said on Friday - and again insisted no soldiers were involved in the attack.
Gen Prawit, also deputy prime minister, said authorities still did not know what truely motivated 62-year-old Watana Pumret, other than that he hated the military. But he was sure it was the right man.
The investigation was continuing, Gen Prawit said with a smile.
Mr Watana, a retired electrical engineer previously with the Electricity Generating Authority of Thailand, was arrested on Thursday and allegedly confessed to planting the bomb that wounded 20 people in the Prawit Wongsuwon Waiting Room at the army hospital last month.
Video clips show the suspect carrying a bag when entering the hospital, walking in the waiting area and leaving the hospital without the bag. (continues below)
There has been speculation that radical red-shirt leader Wuthipong Kochathamkhun, alias Ko Tee, might have been involved in the bomb blast. Gen Prawit said he was not certain whether the fugitive red-shirt leader was not involved or not.
Asked whether anyone else was involved, the minister said an initial investigation found someone close to the suspect might be. He again insisted that soldiers had nothing to do with the blast at the hospital, Thai media reported.
He said authorities took their time before making an arrest because they had to examine footage from several surveillance cameras.
Meanwhile, former prime minister Yingluck Shinawatra has begged the public not to link her elder brother Thaksin to the bombing, saying he has never supported violence.
She made her remark after police and soldiers found pictures of Thaksin when they searched Mr Watana's house on Thursday.
Ms Yingluck said her elder brother was a former prime minister and it was not unusual that some people love him. Thaksin had never supported the use of violence and the Pheu Thai Party always condemned acts of violence, she said.
Ms Yingluck answered questions from reporters when she arrived at the Supreme Court’s Criminal Division for Political Office Holders on Friday morning, to a warm welcome by her supporters and former Pheu Thai MPs and cabinet ministers.
Friday is the 13th day of the hearing of testimony from defence witnesses at Ms Yingluck's trial for dereliction of duty over the controversial rice pledging scheme.