A Michigan man who had been released from jail on $100,000 bond while awaiting trial on rape charges murdered the 16-year-old girl who had been expected to testify against him, the authorities said on Wednesday.

The teenager, Mujey Dumbuya, a high school student from Grand Rapids, Mich., was to testify this month at the trial of the man, Quinn Anthony James, who is in his early 40s. But she disappeared in January and was later discovered dead about 50 miles from her home.

In addition to premeditated first-degree murder, Mr. James has also been charged with kidnapping and conspiracy, said Christopher Becker, the prosecuting attorney for Kent County.

Prosecutors have also charged a second man, Gerald Bennett, with one count of conspiracy, Mr. Becker said. They say Mr. Bennett, of Detroit, received a vehicle from Mr. James as payment for assisting with the murder — and possibly the disposal of Mujey’s body.