U.S. Diplomat's Wife Suspected in Crash That Killed Teenager Leaves U.K.

The wife of a United States diplomat has returned to her home country after being involved in a fatal crash of a 19-year-old, Northamptonshire police said in a statement Saturday.

Harry Dunn, 19, died on Aug. 27 while riding on his Kawasaki motorcycle when he collided with a Volvo XC90 that was traveling in the opposite direction in Croughton, a small village located in central England.

The driver of the Volvo was the unnamed spouse to the U.S. diplomat.

“We can confirm that a 42-year-old American woman being treated as a suspect in our investigation into a fatal road traffic collision on the B4031 Park End, Croughton, on Tuesday, August 27, has left the country," Northamptonshire Police Superintendent Sarah Johnson said in a statement released on Saturday. “Northamptonshire Police followed all of its usual procedures following the incident, including liaising closely with the suspect, who engaged fully with us at the time and had previously confirmed to us that she had no plans to leave the country in the near future."

Johnson said that because of diplomatic immunity issues, investigators followed due process in order to obtain a waiver and arrest and interview the suspect involved in the crash, but they were unable to do so in time before the suspect left the U.K.

“Due process was also followed in seeking the necessary documentation to allow for the arrest and formal interview of the suspect, and the Force is now exploring all opportunities through diplomatic channels to ensure that the investigation continues to progress.

According to a statement sent to NBC News by the State Department, due to privacy and security concerns, the identity of the U.S. diplomat and his wife could not be confirmed by the department.

"We express our deepest sympathies and offer condolences to the family of the deceased in the tragic Aug. 27 traffic accident involving a vehicle driving by the spouse of a U.S. diplomat assigned to the United Kingdom."

The statement confirmed that the family had left the U.K. adding that, "Any questions regarding a waiver of immunity with regard to our diplomats and their family members overseas in a case like this receive careful attention at senior levels."

Johnson said the department later learned that the waiver they'd applied for had been declined.

“Harry Dunn’s family deserve justice and in order to achieve this, a full and thorough investigation, with the assistance of all parties involved, needs to take place," Superintendent Johnson wrote in the statement. "Northamptonshire Police is committed to ensuring justice for Harry and specially trained officers continue to support the Dunn family in their loss, including keeping them fully informed of all developments in the investigation."