Federal Investigations · Agency Guide

U.S. Postal Inspection Service Investigation Defense

Deandra M. Grant
Reviewed by Deandra M. Grant, JD, GC, MS, ACS-CHAL Forensic Lawyer-Scientist
Updated July 29, 2026
Read time 7 min
The Short Answer

The Postal Inspection Service investigates offenses connected to the mail: mail fraud under 18 U.S.C. § 1341, narcotics and contraband shipped through the mail, mail theft, and identity theft using mailed documents. Because mail fraud requires only that the mails were used in furtherance of a scheme, its reach is very wide.

USPIS is easy to underestimate. It is a small agency with one of the broadest hooks in federal law.

Mail fraud carries twenty years per count, thirty where a financial institution is affected, and it applies to private carriers too — not just the Postal Service.

Mail fraud, and why its reach is so wide

18 U.S.C. § 1341 requires a scheme to defraud plus use of the mails in furtherance of it. The mailing need not itself be fraudulent — a routine invoice, a confirmation letter, or a shipped product can satisfy the element.

Critically, the statute reaches private and commercial interstate carriers as well as the Postal Service, so a package sent by a courier supplies the same hook.

Maximum 20 years per count, or 30 where the scheme affects a financial institution. Sentencing runs on the loss table at U.S.S.G. § 2B1.1, as with all white collar matters, which means the loss figure is the fight.

In practice mail fraud is charged alongside wire fraud almost automatically, since modern schemes use both.

Narcotics and contraband in the mail

A large part of USPIS work is interdicting controlled substances shipped through the mail — a channel that grew substantially with online drug sales.

The legal framework matters. Postal Inspectors may detain a package on reasonable suspicion for a brief period, and may use a drug-detection dog on the exterior. But opening a sealed first-class package generally requires a search warrant, because first-class mail carries a reasonable expectation of privacy.

That produces real litigation: how long the package was detained before a warrant issued, whether reasonable suspicion actually existed at the moment of detention, and whether the affidavit's profile factors — handwritten label, heavily taped seams, cash payment, a return address that does not exist — genuinely supported it or were boilerplate.

Controlled deliveries

Where a package is found to contain contraband, agents often make a controlled delivery — delivering it under surveillance and arresting whoever accepts it, sometimes with an anticipatory search warrant for the premises.

Acceptance alone is a weaker case than it looks. The defense question is knowledge: whether the recipient knew what was in the package. People accept packages for others, at addresses they do not control, without knowing the contents — and the government's proof is often just the acceptance plus an inference.

Mail covers and what they can record

A mail cover records information from the outside of mail — sender, addressee, postmark, class — without opening anything. It requires no warrant, because the exterior carries no expectation of privacy.

Mail covers are used to map relationships and establish patterns early in an investigation, and their existence is often the first documentary evidence that a case was open long before the target knew.

Mail theft and identity crime

Theft of mail under 18 U.S.C. § 1708, and the identity and check fraud that follows from stolen mail — including stolen checks altered and deposited, and account takeovers using mailed statements. These frequently carry an aggravated identity theft count with its mandatory consecutive two years.

What to do if agents contact you

Do not answer questions. Say that you want to speak with a lawyer, and say nothing else. That is lawful and cannot be used as evidence of guilt. Lying to a federal agent is a separate felony under 18 U.S.C. § 1001 — no oath required.

Do not consent to a search. If they have a warrant they do not need permission.

Do not destroy anything. A preservation duty attaches the moment you know of the investigation.

Write down what happened — names, agency, time, what was asked, what was taken — the same day.

Then call (214) 225-7117. The pre-indictment window is the most valuable period you have.

Key Terms

The words that come up most on this page, in plain English.

In furtherance
The requirement that a mailing advanced the scheme, without needing to be fraudulent itself.
Controlled delivery
Surveilled delivery of a package known to contain contraband.
Mail cover
A warrantless record of exterior mail information used to establish patterns.
Anticipatory warrant
A warrant issued in advance, taking effect on the occurrence of a triggering event such as delivery.

More on This Topic

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Deandra M. Grant
Written & Reviewed By

Deandra M. Grant, JD, GC, MS, ACS-CHAL Forensic Lawyer-Scientist

She holds a Master of Science in Pharmaceutical Science and a Graduate Certificate in Forensic Toxicology, both from the University of Florida. She is the author of The Texas DWI Manual and has defended Texas DWI cases since 1994.

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