MONTGOMERY COUNTY, TX --A man has been arrested and police are seeking a key witness in connection with an assault on a police officer. The leg of Shenandoah Police Sergeant Raymond Shaw was broken after he was run over by a four-wheel ATV on December 30. On January 2, Shenandoah police arrested Joseph Charles Lynch at his residence in Conroe. Lynch remains in custody of the Montgomery County Jail on a $160,000 bond. The female passenger riding with Lynch on the ATV has not been located. Investigators are seeking help in identifying and locating the female passenger as an important witness. This witness has information pertinent to this case and most likely was an unwilling participant in the assault. Additionally, this witness may have suffered an injury when she was thrown from the four-wheeler after striking Sergeant Shaw. The female witness is described as white, 20 to 30 years old, with light colored hair. If you have information concerning the identity of this female witness or have additional information regarding the assault on Sergeant Raymond Shaw, please contact the Shenandoah Police Department at (281) 367-8952. If you wish to remain anonymous, please call Montgomery County Crime Stoppers at (800) 392-7867.