The sister of Supreme Court Justice Amy Coney Barrett was recently targeted with a bomb threat, the Charleston, South Carolina, Police Department said on Wednesday.

Over the weekend, an executive assistant at the Charleston County Sheriff’s Department received an email just before midnight on March 8 with “a threat of a potential explosive device in a mailbox” at the home of Amanda Coney Williams, the sheriff’s department said in a statement to ABC News.

The employee only works during the week, so she did not see the email until Monday morning, the sheriff’s department said. After discovering the email, she notified Sheriff Carl Ritchie “within five minutes of arriving to work,” to which Ritchie forwarded the email to the Charleston Police Department.

“Using a 1×8-inch threaded galvanized pipe, end caps, a kitchen timer, some wires, metal clips and homemade black powder, I’ve constructed a pipe bomb which I recently placed in Amy Coney Barrett’s sister’s mailbox at her home,” according to the email obtained by the Charleston Police Department.

The email also said the “device’s detonation will be triggered as soon as the mailbox is next opened,” with the suspect signing off the email with “Free Palestine,” police said.

Officers arrived at the residence at approximately 9:30 a.m. on Monday and inspected the mailbox, police said.

CPD’s Explosive Device Team along with local fire and emergency medical services crews were also on the scene, according to police.

The incident was determined to be a false alarm, police said.

Investigators spoke to David Williams, the husband of Amanda Coney Williams, who said he was not sure who would target their residence, but stated “an unknown person possibly related to the sender of the email had attempted pizza deliveries to some households related to Amy Coney Barrett, sometime over the weekend,” police said on Wednesday.

The investigation is still active, police said.

Justice Barrett was appointed to the U.S. Supreme Court in 2020 during President Donald Trump’s first term. She is a devout Catholic, mother of seven children and was the youngest Supreme Court nominee since Clarence Thomas in 1991.