A Janesville man was arrested early Friday morning on his suspected sixth intoxicated-driving charge, Janesville police said.

Officers reported seeing Mark S. Carlson, 59, of 100 N. Oakhill Ave., swerving as he drove east on Black Bridge Road at 1:59 a.m. Friday, according to a police news release. They stopped Carlson after noticing his license plates did not match his vehicle.

During the traffic stop, Carlson showed signs of impairment but refused to perform a field sobriety test. He later submitted to a blood test, according to the release.

Carlson was arrested on a charge of sixth-offense intoxicated driving and cited for operating after revocation due to alcohol, displaying an unauthorized registration plate and no insurance.

Blood test results are pending. Carlson is being held at the Rock County Jail.