United States v. Tanguay, 811 F.3d 78

Jonathan Tanguay was convicted of possession of child pornography after a search of his home and computer based on a state search warrant.
The warrant rested on an affidavit by Sgt. Carrie Nolet that relied heavily on statements from a private informant, Joshua Wiggin.
The district court originally reformed Nolet’s affidavit to add omissions it deemed recklessly omitted but still found probable cause; this Court affirmed most rulings in an earlier appeal (Tanguay II) but remanded to decide whether Nolet had a duty to investigate Wiggin’s credibility.
On remand the district court found Nolet should have investigated and would have discovered Wiggin’s 1998 juvenile false-report adjudication, which should have been included in the affidavit, but concluded that even with that fact added probable cause remained.
Tanguay argued on further appeal that adding all uncovered adverse information (including additional arrests and a later 2011 false-report conviction) would destroy probable cause; the court rejected inclusion of post-affidavit evidence and other immaterial arrests and affirmed denial of suppression.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Duty to further investigate informant credibility	Nolet’s known facts triggered inquiry; failure could be reckless	Nolet had no duty to dig deeper before submitting affidavit	Court: Duty can arise; remand required (earlier opinion) and district court found duty here but not reckless such that warrant invalidated
Whether juvenile false-report adjudication must be added to affidavit	District court (on remand) found it should be added	Tanguay argued adding it destroys probable cause	Held: Even after adding the juvenile adjudication, affidavit still established probable cause; denial of suppression affirmed
Whether other old arrests/shoplifting/poss. of stolen property must be included	Tanguay: these arrests undercut Wiggin’s credibility and should be included	Government: arrests did not by nature impugn veracity and were immaterial	Held: District court reasonably refused to add them; exclusion not reversible error (and harmless if error)
Whether post-affidavit convictions (2011 false report) are usable under Franks	Tanguay sought to include later conviction to impeach informant	Government: affiant cannot be charged with knowledge of events occurring after warrant	Held: Information unknown at time of affidavit cannot be part of Franks analysis; excluded

Ornelas v. United States, 517 U.S. 690 (de novo review of probable cause with factual findings for clear error)
Franks v. Delaware, 438 U.S. 154 (warrant affidavit must be reformed to include recklessly omitted material facts)
United States v. Tanguay, 787 F.3d 44 (1st Cir. 2015) (prior panel: scope of duty to investigate informant credibility; remand instructions)
United States v. McLellan, 792 F.3d 200 (Franks omission standard discussion)
United States v. Rumney, 867 F.2d 714 (a criminal record does not necessarily impugn veracity)