WORCESTER — Hidden camera footage shows a Harvard postal carrier smoking from a glass pipe while out delivering mail, according to an affidavit filed in U.S. District Court.

Cameras, installed in the post office and a mail truck, link the carrier to $37,000 in charges to stolen credit cards the affidavit states.

Stephanie Lacroix, 37, of Fitchburg, is facing mail theft charges following a federal investigation into her work as a mail carrier this spring and summer.

According to an affidavit filed by Brian Martineau, a special agent with the United States Postal Service’s Office of Inspector General, an investigation on Lacroix began this spring after police in Harvard received numerous complaints from residents about credit cards they expected to receive by mail being stolen.

As of August, 33 Harvard residents had reported such thefts. According to Martineau, all of these people lived on Lacroix’s mail delivery route.

Martineau’s office requested that cameras be installed in the post office Lacroix worked in, as well as the truck she drove on her route to monitor her behavior. While making her delivery rounds on Aug. 6, Lacroix was observed opening a series of envelopes she was responsible for delivery and putting all of the open mail into a grocery bag, which she then put in her purse, according to the affidavit. She was also observed removing a Starbucks gift card from one piece of mail, the affidavit stated.

According to Martineau’s affidavit, Lacroix was also recorded while taking a glass pipe from her purse.

Lacroix was located by police that same day and brought in for questioning, during which she denied having opened any mail or smoked any substance while in her delivery truck.

However, Lacroix was observed through security camera footage at several area businesses to be using the stolen credit cards on three occasions, the affidavit states. She was recorded using stolen cards at gas stations in Lunenburg and Boxboro on June 28 and at a Leominster Wal-Mart on July 24.

Lacroix was arraigned in U.S. District Court in Worcester on Friday and released on conditions that she surrender her passport and undergo drug testing.

It was not immediately clear what Lacroix’s job status was. A call to the Harvard postmaster was not returned on Monday.