SAN FRANCISCO (CBS SF) — A Colorado woman has pleaded not guilty to a smuggling charge in a case that began when San Francisco airport package screeners uncovered illegal human fetal specimens inside a package she was attempting to mail to the United Kingdom.

Emily Suzanne Cain made a court appear on the charge Wednesday in San Francisco federal court where she entered a not guilty plea. She was scheduled to make her next court appearance on Nov. 20th.

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Read Criminal Complaint In SFO Illegal Fetus Smuggling Case

According to the charging affidavit, a package mailed from the Canon City Colo., post office by Cain arrived at San Francisco International for transport overseas on Oct. 15, 2018.

“Cain mailed the package labeled as school teaching aids and t-shirts that in fact contained human fetal specimens, and Cain knew the package was human fetal matter,” the court document said.

The package had passed undetected through postal distribution centers in Denver and San Francisco. Customs agents at San Francisco International are required to screen all packages before they are placed on international flights.

“(Agents) performed an x-ray on the package at the Air Mail Facility and the x-rays revealed what appeared to be a human shape,” the charging document stated.

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The affidvit stated there was also a handwritten note with the package.

“It included a handwritten note stating the sender was sorry for the delay, but the sender had issues opening the ‘Big Block.’ The card was signed Emily,” the court document stated.

Investigators recovered latent fingerprints that were eventually matched to Cain off the box, t-shirt and card. They also uncovered evidence that Cain was trying to illegally sell fetal specimens on her Facebook page.

According to the charging documents in one of the exchanges, Cain told a Facebook user when she was asked about the specimens — “I’m always happy to show you. Please never hesitate to check in with me and see what we have. We don’t always post publicly. Especially with pieces like these … and … too controversial to be up for everyone to see. I try to keep them for special clients and others we know may have interest in them.”

Investigators said the fetuses were up for sale for $20,000. Cain also allegedly sold another male fetus to the Facebook user for $500 in August 2018.

Creighton University officials have confirmed that the three fetuses seized in San Francisco had originally been donated to its anatomy department after they were still-born in the 1920s and 1930s.

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The charging document did not reveal how Cain had obtained the remains, but said the university no longer will keep donated fetuses and had ordered the ones they had to be “cremated and not sold.”