Some say that Mutt has always worked better with animals than people. When he joined the Army, they saw this, too, and made Mutt a dog handler. He attended Jungle Warfare Training school and later became an adviser to Special Ops school and the Security and Enforcement Committee. Mutt's dog, Junkyard, has been with Mutt since he was a pup. They worked so well together, that Junkyard joined the Army right along with his owner.

    Mutt and Junkyard's first assignment with the G.I. Joe team was to track down Zartan's secret lair in the Florida Everglades. Several top Cobra operatives were meeting there and the Joes were after them. Along with the Joes Torpedo and Tripwire, the pair captured Wild Weasel and Firefly and tied them to a cypress tree. Junkyard soon picked up a scent and led the Joes to Zartan's shack where Cobra Commander, Destro and the Baroness were all hiding. As the Joes stayed in hiding watching the shack, Junkyard bounded up to the Cobras. He was happily pointing in the Joes direction and the Cobras were off into the swamp to see where the dog at come from. Mutt was furious, believing Junkyard had betrayed them to the Cobras, but as the Joes made a hasty retreat, Junkyard led the villains into a puddle of quicksand and then set off a trap that the Joes would have surely been caught in. The Joes escaped the Cobras and returned to the coast where their freighter waited.

    While Mutt and Junkyard were at Joe headquarters, they were part of the Pit's security detail. Mutt and Junkyard were later sent on a mission to a nearby neighborhood  in Staten Island with a small team of Joes led by Duke. They were raiding a house owned by Crimson Guardsman Professor Appel. Snake-Eyes, Mutt and Junkyard stormed the house to flush out the Cobra agent, but were met by unexpected gunfire. Junkyard saved Snake-Eyes and Mutt by dropping a hand grenade down a sink before it could explode. Some time later, Mutt and the Junkyard participated in the invasion of the Cobra controlled town of Springfield, along with nearly every active member of the Joe team. When that invasion ended in failure the team was put on suspension for a short time before returned to active status.

    In an even bigger operation than the Springfield invasion, the Joe team entered the Cobra Island civil war on the side of Serpentor against Cobra Commander. Mutt and Junkyard were part of the team that saw to the destruction of Cobra's anti-aircraft defenses, allowing the Joes' transport craft to land at Cobra's airfield. After days of fighting, the team had nearly won the war when Serpentor was killed by Zartan. A truce was called between Dr. Mindbender and Cobra Commander, and the Joes were forced to leave in disgrace. When the Joes returned home, they were accused of invading the island against orders and much of the team was held in custody until the remaining Joes could clear their name.

    After the Joes were exonerated, Mutt and Junkyard took part in a stakeout with Cross Country and Law & Order. The team was keeping watch over an abandoned gas station being used as a hideout by the Dreadnoks. When the Dreadnoks arrived late one night, the Joes crept forward, but were spotted by the Dreadnoks. Buzzer hopped on his motorcycle and headed right for Mutt and Junkyard. Intent on protecting Mutt, Junkyard led Buzzer away from his owner. The Dreadnok quickly caught up to the dog an wounded him with a slash from a chainsaw. A fire fight ensued, during which most of the Dreadnoks were driven off. A few of them, including Buzzer were captured. Though Junkyard would survive, Mutt got a few kicks in at Buzzer for nearly killing his dog. A short time later, while Junkyard was still recovering from his injuries, the captured Dreadnoks were released from jail. Mutt overheard that Battle Force 2000 was being sent on a recon mission to keep an eye on the Dreadnoks. He insisted on coming along and got another kick at Buzzer, but all but one of the Dreadnoks escaped and the Joes were arrested by local police and held for a short time.

    Some time later, Mutt went on leave along with Junkyard and Spirit. They visited Millville, New York, where Mutt has spent much of childhood with his Uncle Jeff. Millville had fallen on hard times after the mill was shut down. Mutt's uncle was alone after his wife had died and his children moved away, and Jeff seemed sullen and quiet. While Mutt visited his uncle, the true Cobra Commander had returned and planned to subjugate Milville and make it the next Springfield. Cobra troops and vehicles invaded the town. Many citizens were willing to listen to Cobra Commander's propaganda, and those that didn't were brainwashed by the Brain-wave Scanner. Mutt and Spirit tried to contact the Joes, but Cobra had shut down all means of communication outside the town. The two Joes managed to ambush and steal a HISS tank, but when they got to Uncle Jeff's home, they found he had been brainwashed and turned them into Cobra Vipers. With the help of Russ, a local veteran who had resisted the Brain-wave Scanner, the Joes escaped their captors. After Russ led them to the lair of a local street gang to hide out for a while, Mutt and Spirit convinced the gang to help them stage a revolt against Cobra. They raided the reopened mill and discovered that Cobra could turn the brainwashing on and off at will, allowing them to make the town seemingly normal to fool anyone who may be suspicious of the town. As they made this discovery, Hawk and Law & Order arrived, looking for their missing teammates. They found the town to be perfectly normal, except for Mutt, Spirit, Russ and the street gang, who were attacking the town. Faced with the local police and no proof of Cobra's involvement in the town, Mutt and Spirit were taken into custody. Mutt and Spirit were suspended indefinitely until the truth could be determined.

    Months later, the Joes discovered evidence of Cobra's operation in Millville and staged a raid on the town. Mutt and Spirit were a part of the operation, since it appeared that they were right all along. After a battle against Cobra forces, the team liberated Millville. Shortly afterward, the state of New York formally dropped all charges against Mutt and Spirit, allowing them to return to duty. Mutt remained on the team until it was disbanded in 1994. Mutt and Junkyard's fondness for each other was not always obvious. Mutt often seemed frustrated and annoyed with Junkyard, while Junkyard remains loyal to Mutt. Deep down, Mutt considers Junkyard his friend. While Mutt usually gets along well with Spirit and Law, he generally acted grumpy and irritable to other Joes. Even so, Mutt is a good soldier and loyal to his teammates. His teammates recognized those qualities in Mutt, but most got along better with Junkyard.

    In the years after the team was shut down, Mutt continued his service in the regular Army, though an aging Junkyard was sent to live on a farm owned by a friend of Mutt's. In 2001, the Joe team was reinstated and Mutt was invited to join months later. Mutt spent some time completing his training of Junkyard II, the son of the original Junkyard, which is why Mutt sometimes calls the younger dog "Junior". Just before rejoining the Joes, Mutt met up with a number of other Joes to reminisce, but they stumbled upon a hidden cell of Cobras in a small town. After a brief fight, the Joes escaped and Mutt and Junkyard II soon returned to the team. Some time later, members of the Joe team fought Cobra forces that were drawn into an attack on a train guarded by the Joes, believing that Destro was being held prisoner onboard. At the battle's end, Hawk was shot in the back by Cobra Commander and paralyzed. In Hawk's absence, the Jugglers began to take control of the team to reign it in, if not disband it altogether. Eventually, the team's roster was cut down to only a dozen Joes, and Mutt was one of many reassigned to other units. After the remaining Joes stopped a plot by Cobra to unleash the weapon known as the Tempest, and defeated a new threat, the Red Shadows, the military again disbanded the team. One year later, the Joe team was reformed with a smaller roster of active members. Mutt, like most former Joes, is a reserve member of the new team.

Artwork: G.I. JOE #121 (dossier).