Sergeant Benjamin.
Sergeant Benjamin was the main MP that helped Dr. Hasslip track down the chimpanzee Peanuts. Though in the end they recovered the wrong chimp.
He pointed out to Dr. Hasslip that a message had been sent off base using Hasslip's password but had been done when the Sergeant was in Hasslip's presence. This started to make Hasslip realize the security leak might be Peanuts.
He brought word of the ransom demand and captured Richard Langly soon after.
When they finally retrieved who they thought was Peanuts, he asked Dr. Hasslip what they should do with the four The Lone Gunmen and Yves Adele Harlow. Dr. Hasslip told him to let them go but shoot them on sight if they ever showed up again.