Here is a Reuters article from May 22- https://www.reuters.com/world/americas/peru-opens-criminal-investigation-president-castillo-2022-05-29/
"Peru’s attorney general’s office announced on Sunday it was including President Pedro Castillo in an investigation into alleged crimes including influence peddling, collusion and “criminal organization.”
Peru’s Public Ministry on Twitter said Pablo Sanchez, the country’s top prosecutor, will lead the investigation into Castillo given the “seriousness of the accusations” made in an investigation against former Minister of Transport and Communications Juan Silva and six legislators from the opposition party."
It did not seem like “rapid” turn to me, the guy always seemed like pretty run of the mill LatAm socdem who entered a wide tent coalition to defeat the right, afaik it was mostly GenZedong sub that made way too optimistic assessment of him.