Legal Question in Criminal Law in Michigan

Re: Not Seized at the Time

"When" the police seize evidence is not as important as "why" / "how" (meaning: under what legal authority) they do so.

Was there a search warrant (an order signed by a judge or magistrate giving the police authority to seize the item)? Was the item seized with consent of the item's owner? Etc. These would both be legal, proper ways for police to seize evidence.

It's hard to give a more definite reply without more case facts. You or your son should review the police report, search warrant or other case facts with a criminal defense attorney so the attorney can assess whether the 4th Amendment was violated and (after a charge is issued) a motion can be filed to suppress that evidence from being introduced in trial by the prosecutor.