BATON ROUGE -  Police believe an armed robbery that ended with a man stealing a set of keys from a postal worker last year has led to a recent surge in stolen checks.

The initial robbery happened back in October when Tarek Sonnier, 24, allegedly pulled the gun on a mail carrier while the worker was making deliveries. The victim said she tried to run, but she was sprayed in the face with mace before someone took her mail keys. 

Sonnier was arrested a day after the attack and later released on a $50,000 bond. 

In the months that followed, sheriff's deputies began investigating a series of crimes that involved thieves stealing checks from mail drop-off boxes and then "washing" them, allowing the thief to change whom the check was addressed to.

"We had to close our account, we had to get affidavits, we had to get things notarized," Jerry Mayer, one of the victims, told 2 On Your Side. "We lost nearly $4,000 because of it."

Earlier this month, investigators tied the thefts to blue mailboxes at the Perkins Road, Millwood Drive and Florida Street post offices. One suspect, identified as Infiniti Monae Rogers, has been arrested, and investigators are looking for two more.

Detective Sam Stafford with BRPD's financial crimes division told The Advocate this week that many of those crimes were made possible thanks to that armed robbery last year. The keys taken during that brazen attack would grant access to the blue mailboxes that had been targeted in recent months. 

“That’s where all this is coming from,” Stafford told the newspaper. "The people who got these checks, they're washing them, they're selling them on the dark web, and they're doing it locally, too."

Law enforcement is now reportedly asking impacted post office branches to change their mailbox locks. When asked why the locks on those mailboxes weren't changed sooner, the postal service gave WBRZ the following statement.

Stafford estimated the department has made more than 100 arrests related to check washing and other financial crimes in the past month.

Police are also urging residents to avoid mailing checks whenever possible.