Deputy National Police Commissioner Maj General Somyot Poompanmoung said soldiers arrested Yongyut Boondee in Chiang Mai and forwarded the suspect to police yesterday morning.
Yongyut has told police that Chatchawan Prabbamrung, who was arrested earlier, had encouraged him to stage the attacks without any pay.
He also said he did not receive any training of use of military weapons.
Somyot said Yongyut went into hiding in Buri Ram and then Chiang Mai province after the PDRC rallies ended.
Yongyut is now facing charges of pre-meditated attempted murders, staging grenade attacks that caused property damage and illegal possession of ammunition and military weapons.
An ongoing investigation showed Yongyut used to attend the red-shirt rallies led by Wutthipong Kotchathamkhun, alias Ko Tee.