On Tuesday, court records showed that three former surgery patients of a Colorado hospital have sued the hospital saying that they were among the roughly 3,000 people who have probably been exposed to blood-borne disease spread by a drug addict former medical technician at the hospital.

The suburban Denver’s Swedish Medical Center has been accused of carelessness in its hiring and supervision of a surgical technologist, who was recently found indulged in a practice wherein he was trying to switch a syringe that contained the powerful opiate fentanyl citrate with other substance during the surgery of a patient in January.

Last month, the 28-year-old technician, Rocky Allen got indicted by a federal grand jury in Denver on one count of tampering with a consumer product and one count of getting a restricted substance by cheating, both of which are offenses.

According to the civil complaint filed in US District Court in Denver, federal authorities in the criminal case testified previous month during a criminal hearing that Allen was a carrier of an unnamed ‘blood-borne pathogen’.

Due to the incident the hospital was prompted to notify nearly 2,900 patients who went through surgery at the facility in the time period between August 2015 to January this year during Allen’s employment to undergo HIV and hepatitis B and C screening.

The three patients, who have sued the hospital, had undergone surgery in that time period. They want monetary damages for emotional distress.

The lawsuit said that all the three plaintiffs have tested negative for the blood-borne diseases, however, they have been told to undergo screening for around another six months.

The court documents showed that earlier Allen has served as a surgical technician at different hospitals in Washington State, California, the US Navy, and Arizona.