Thai police said they had questioned and freed one man who handed himself in after being seen on CCTV at the Bangkok shrine moments before a deadly bomb blast, but the prime suspect remains at large.
Authorities say they believe international terrorists were not involved in the attack that killed 20 people - 14 of them foreigners - although there has been no claim of responsibility.
A Thai man wanted for questioning after he was seen on security camera footage "met police and was released", a police spokesman said, adding a second man from China in the same shot had already left the country - but neither were "likely involved".
The main suspect, believed to be a foreigner in a yellow shirt seen leaving a backpack at the scene was still at large, he added.
The two men seen on the CCTV footage were initially believed to be possible accomplices of the suspected bomber.
They were seen standing in front of the lead suspect as he took a backpack off and placed it under a bench. They then left the crowed shrine in central Bangkok.
Moments later the bomb exploded killing at least 20 people, mainly foreigners, wounding scores more and sparking a manhunt for the bomber.
"The Thai man is from Chiang Mai," the police spokesman said said, explaining he had taken the Chinese man to the Erawan shrine on behalf of a mutual friend.
The Chinese man returned home a day after the bomb.
Thai authorities have given conflicting and contradictory snippets of information on their search for the bomber.
But they say they are still confident the man in the yellow shirt, described in his arrest warrant as a foreigner is the prime suspect.
People were seen paying their respect to the Hindu shrine after it reopened yesterday. Visitors left messages of condolences, flowers and candles at the site.
The government said Monday evening's attack was aimed at wrecking the economy, which depends heavily on tourism.
The Erawan shrine at a main city-centre intersection is popular with tourists from China and other East Asian countries. About half the victims were foreigners.
A spokesperson for the national police said they have requested assistance from Interpol for help in tracking down the suspect.
The military government was initially reluctant in asking for outside help in the investigation.
Police said they were also considering the possibility that ethnic Uighurs were behind the bombing. Thailand forcibly returned 109 Uighurs to China last month.
Hundreds, possibly thousands, of members of the Turkic-speaking and largely Muslim minority have fled unrest in China's western Xinjiang region, where hundreds of people have been killed, prompting a crackdown by Chinese authorities. Many Uighurs have travelled through Southeast Asia to Turkey.
Checks at airports and other exit points found that no one matching the description of the main suspect had left the country since the attack, police said.
