TYLER, Texas (AP) — A Texas nurse accused of intentionally injuring patients has been charged with murder and aggravated assault with a deadly weapon.

The Tyler Morning Telegraph reports that a jury indicted William Davis last week. The nurse was arrested in April as a suspect in the death of 47-year-old Christopher Greenaway, who was recovering from a heart procedure at the Louis and Peaches Owen Heart Hospital in Tyler.

An arrest affidavit says Davis is also accused of injuring six other patients, one of whom died, at Christus Mother Frances Hospital in Tyler. The hospital is part of the same health system as the Owen Heart Hospital.

Authorities allege Davis introduced air into the circulatory systems of patients recovering from heart surgery, causing stroke-like symptoms.

Davis is being held in the Smith County Jail on a $2 million bond.