Police believe three homeless people murdered in Pathum Thani's Thanyaburi district this week were killed by a single person they describe as insane and sexually obsessive.
Pol Maj Gen Songphol Watthanachai, deputy police spokesman, said on Friday the manner of death in all three cases was similar - hands tied behind their back with electrical wire and deep cuts to the body, reflecting a mental disorder.
Police on Thursday described the murderer as a serial killer.
The three victims, aged 35-40, were found near Princess Mother National Institute for Drug Abuse Treatment on Phahon Yothin Road from Tuesday to Thursday. The first and third were male, the second female.
Police were combing the vicinity around the crime scenes, especially areas frequented by homeless people, the spokesman said.
Deputy national police chief Chalermkiat Sriworakan said on Friday the condition of the bodies indicated the murderer wanted public attention. Police assumed the killer was insane.
The first victim might have known the killer. The dead woman had been sexually molested and the killer was believed to have tried to rape another homeless woman, Pol Gen Chalermkiat said. He believed the murderer was a scavenger, like the victims.
Pol Maj Gen Amnart Chancharoen, investigative chief of the Provincial Police Region 1, quoted witnesses as saying the suspect was about 160 centimetres tall, usually travelled on a bicycle, appeared drunken and had often drunk with victims.
From the footage of about 10 surveillance cameras, police saw the man was riding around the crime scenes repeatedly. They were hunting for him in Khlong Luang, Lam Luk Ka, Muang and Thanyaburi districts around the clock, Pol Maj Gen Amnart said.
The latest footage saw the man in front of Zeer Rangsit shopping centre in Lam Luk Ka before he disappeared with his bicycle, the officer said.
Surveillance camera footage shows the suspected killer on his bicycle.
Police's sketch of the suspected serial killer