TUPELO, Mississippi (Reuters) - Mississippi police have arrested a man they believe is responsible for two highway killings this month, the Department of Public Safety said on Friday.

The suspect, James Willie, 28, of Sardis, Mississippi, was arrested Tuesday morning in Tunica, the department said in a statement. Police had responded to a reported rape.

Willie is charged with aggravated assault, kidnapping and rape. He will be charged with two counts of capital murder on Friday, the statement said.

Willie had a Ruger 9mm handgun that matched the weapon used in two shooting deaths in northern Mississippi.

A 74-year-old man was found dead in his pickup truck on Interstate 55 on May 8. The body of a 48-year-old woman was discovered three days later by her car on the shoulder of a state highway.

Police had theorized that the shooter had lured the motorists to the roadside by impersonating a police officer. But Warren Strain, a spokesman for the Department of Public Safety, said that apparently was not the case.

"There is still more to follow as to motive and other details," he said.

(Reporting By Emily Le Coz; Editing by Vicki Allen)