BANGKOK, Dec 18 — Thai police arrested a convicted serial killer today in connection with another murder after his early release from jail for good behaviour, authorities confirmed. 

Somkid Pumpuang was sentenced to life in 2005 for the killing of five women believed to be involved in the sex and nightlife industry, leading the media to dub him Thailand’s "Jack the Ripper”.

Authorities considered him an "excellent prisoner” and released him in May this year, but he is now the chief suspect in the murder this week of a 51-year-old hotel maid in the country’s northeast.

Authorities distributed his photo under the heading "Most Wanted” and offered a 50,000 baht (US$1,650) reward for information leading to his capture.

Today, released photos showed police officers detaining the suspect on a train in the town of Pakchong in Nakhon Ratchasima province.

"Somkid Pumpuang was arrested thanks to information from the public,” Major General Puttipong Musikul from Khon Kaen police force told AFP this morning.

Local media described how a fellow passenger on the train spotted the suspect wearing a cap and face mask and sent a photo to police.

Thailand’s corrections department said it was urgently reviewing its sentence reduction policies but also said it was operating at three times capacity with 370,000 inmates.

Thailand has one of the largest prison populations in the world and overcrowding remains a serious problem.

The number reached an all-time high earlier this year, according to a report this month from the International Federation for Human Rights and the Union for Civil Liberty.

Nearly 80 per cent are jailed for drug-related offences. — AFP