The meeting relates to a case brought against Thaksin in 2016 that has yet to advance, in which authorities are now considering new evidence.
A spokesperson for the office on Monday said more investigations were needed into the complaint against Thaksin.
The influential billionaire was released on parole on Sunday after six months in detention, his first day of freedom in his homeland 15 years after fleeing in the wake of his overthrow in a military coup.
Thailand's best-known and most polarising premier, Thaksin has loomed large over politics during the years spent mostly in self-imposed exile to avoid jail for abuse of power, charges he maintained were cooked up by the country's old guard to keep him at bay.
In a video in local media on Monday, Thaksin was seen at the prosecutor's office in a wheelchair and wearing a surgical mask.
He left hospital on parole before dawn on Sunday and was seen in a vehicle with a neck brace and his arm in a heavily-padded sling. It is unclear what health issues Thaksin is suffering from and details have not been disclosed.
The complaint concerns a 2015 interview he gave while in South Korea and was filed by a junta that ran Thailand after the military overthrew a government led by Thaksin's sister. Thaksin has repeatedly pledged loyalty to the monarchy.
Insulting the crown is a serious offence and a major slur in Thailand, where the constitution states the king must be held in a position of "revered worship". The lese-majeste law is among the world's strictest, with each perceived offence punishable by up to 15 years in prison.
