Cut the BS--Mangione is going to trial with all the evidence being legally obtained.

 OK, My legal qualifications are: JD from the University of Maryland, LLM University of Exeter, England. Admitted to the PA bar in 1990, retired in 2023. Admitted to the DC bar,  EDPA (Fed), and MDPA (Fed). That said, I can give a legal opinion.

The picture is of the Blair County, Police Criminal Complaint, which can be found here:
https://www.pacourts.us/Storage/media/pdfs/20241209/233900-mangione12924.pdf

According to this document, the police were responding to a report of a male who resembled the person wanted for the shooting of Brian Thompson. 

 Mangione removed the mask and the police said they recognised him from the media. Then Mangione gave the police the fake ID used at the NYC hostel. Any searches according to this would be incident to arrest or an inventory search.

You get what the police will probably say in the clip of the press conference which starts at 10:50.

Unless the defence can come up with something substantial, Mangione's arrest appears to be legal based upon what I see here.

 More court documents can be found here:
https://www.thebaltimorebanner.com/community/criminal-justice/luigi-mangione-court-documents-gun-charge-ME4VXEHIOFBK7FIO5STIXXWAPQ/