A suicide note left by the doctor raised questions about the record-keeping.

An Illinois pediatrician who died by suicide last year may have forged patient’s vaccination medical records, according to investigators.

The Cook County Sheriff’s Office began investigating the vaccinations provided by Dr. Van Koinis, 58, who died by a self-inflicted gunshot wound in September, after a suicide note left behind “raised questions” about the record-keeping of vaccinations at his medical practice in Evergreen Park, about 15 miles south of Chicago, the sheriff’s office said in a statement provided to ABC Chicago station WLS.

During the investigation into Koinis’ death, authorities found it was unclear who did and did not receive vaccinations due to record-keeping issues, according to the statement.

Investigators also found that Koinis, in some cases, did not provide vaccinations to children at their parent’s request. It is unclear how many patients may have been affected.

Cook County Sheriff Tom Dart told the Chicago Sun-Times that Koinis “regretted his conduct with immunizations,” which he had been “adverse” to during the last decade of work at his practice.

Dart told the local newspaper Koinis may have forged vaccination documents at the request of parents.

Authorities are now recommending that former patients of Koinis discuss this possibility with their current physicians and inquire about methods to test for prior vaccinations, “out of an abundance of caution.”

Koinis had been licensed to practice in Illinois since 1991, authorities said. He mostly served patients on Chicago’s southwest side and near southwest suburbs, according to the sheriff’s office.

Alzein Pediatrics, the pediatric group that received Koinis’ records, posted a tribute to him following the news of his death last year.

The practice has now posted an option on its website for former patients of Koinis to download a medical records release form.

The investigation is ongoing, and the Illinois Department of Public Health has been notified.

If you are in crisis, please call the National Suicide Prevention Lifeline at 1-800-273-TALK (8255) or contact the Crisis Text Line by texting TALK to 741-741.