A federal grand jury in Boston has begun investigating the Framingham compounding pharmacy that made the tainted steroid injections blamed for at least three dozen deaths in seven states, according to several people familiar with the matter, including one who has been called to testify.

The grand jury has begun issuing subpoenas to people who worked at New England Compounding Center and at least one related company, Medical Sales Management of Framingham, which handled sales and administrative support for the pharmacy, the people said. The grand jury is expected to hear from at least some witnesses in federal court in Boston next week.