Stephens' phone pinged near Erie, PA ... according to a report, which would put him about 100 miles east of Cleveland. He's been charged with aggravated murder after killing 74-year-old Robert Godwin Sunday in Cleveland, and uploading video of the fatal shooting.
The manhunt's now expanded to 5 states -- Cleveland authorities say Stephens could still be in Ohio ... or on the run in Pennsylvania, New York, Indiana or Michigan.
In a separate Facebook video that has since been taken down, Stephens claimed to have killed more than 10 people, but authorities have no knowledge of any other victims. He reportedly told his mother he was killing because he's mad at his girlfriend.