Bloomberg News

Shares of Johnson & Johnson (JNJ - Get Report) fell sharply Friday after the U.S. Department of Justice reportedly launched a criminal investigation into whether the pharmaceutical giant intentionally misled the public about potential cancer risks tied to one of its iconic products, its talcum baby powder.

News of the probe came even as a Johnson & Johnson spokesperson confirmed the company was readying a rollout of an experimental HIV vaccine in the U.S. and Europe this year, potentially marking a medical milestone in an elusive hunt that has spanned decades.

But news of the federal probe appeared uppermost in the mind of investors, who sent shares of J&J plunging 4.19% to $134.24.

The federal investigation, first reported by Bloomberg News, comes as thousands of oncology patients take J&J to court, contending in a civil suit that asbestos in J&J's talcum powder is the cause of their cancer.

J&J has strongly denied the allegations and has argued that tests and studies around the world have shown its talc is safe and asbestos free.

Meanwhile, news of the federal probe overshadowed J&J's potental HIV vaccine breakthrough. The pharmaceutical giant in April teamed up with ViiV Healthcare to file an application with the FDA for the new drug, which would be injected once a month.

"An public announcement on the public private partnership that will enable the study is underway and will also be part of planned activities for the upcoming IAS congress in Mexico city," a J&J spokesperson stated in an email.

The investigational Janssen preventive HIV vaccine will undergo a Phase 3 efficacy study, with the new drug to be tested out in multiple countries around the world, including the United States, Mexico, Peru, Argentina, Italy, Poland and Spain.

Once the study begins, it will become Janssen's second major HIV vaccine test, with the Phase 2b Imbokodo study taking place in five countries in southern Africa. That test "recently achieved full volunteer enrollment," wrote the J&J spokesperson in an email.