One of the 218 escaped prisoners from SAR TOP to Earth. The species of the alien that inhabited the Sheriff's body is not known, but is most likely an Enixian as he is shown wearing sunglasses throughout the episode (which only Enixians are shown doing). Furthermore, his name - 'Dawson' - is not clarified as been either his original name or the name of the Sheriff.
Dawson's crime that resulted in him been imprisoned on SAR TOP was never revealed.
On Earth, he took the human form of the Chicago Sheriff and aided Zin by making Abbey Swenson - the mother of Jamie, whose body was taken over by Cirronian prisoner Lontoria - believe that Zin was a respected film producer from New York. He also was used as a grunt by Zin for other deeds. Thanks to his human form been that of a law enforcer, it allowed Dawson to get away with dirty deeds as well as been trusted by others easily - such as Father Creighton and Abbey Swenson.
When Lontoria gained media attention (as well as the attention of Cole/Daggon) for her 'miracles', Dawson told Mel and Cole (who were at their house with the reporters) to stay away from the Swensons, while taking Mel's license to be checked. Cole almost immediately recognized him as been a fugitive but whose life force was weak. Due to the reporters been around, however, Cole couldn't take Dawson's life force.
When Lontoria was taken to safety by Father Creighton after seeing Zin (who was using the alias "Mr. Raven") and Cole with Jamie, believing them to only want to harm or use Lontoria and her powers for their own means. Hiding her in the old St. Clements church, he rang the Sheriff and asked for help - revealing where he and Jamie were. Unbeknown to him, Dawson then proceeded to contact Zin and pick him up before both men proceeded to the church. Telepathically hearing Cole and Lontoria talking to each other outside the church, Dawson informed Zin before both men armed themselves - Dawson using a Sheriff's rifle while Zin used a Vardian energy weapon (ironically based on Lontoria's research).
Seeing the Sheriff outside, Father Creighton goes outside to talk to him - despite the warnings of both Cole and Lontoria. Almost as soon as he stepped outside and shouted for the Sheriff, Dawson opened fire - shooting him in the leg. As Cole and Lontoria quickly tried to get him back inside the church, Zin opened fire with his own gun, hitting Cole on his arm but not inflicting a direct hit. The two men then split up to enter the church. As Lontoria helped Father Creighton with his injury, Cole went to deal with Dawson.
Having gained entry, Dawson searched around inside for Cole. However, Cole jumped him from behind and knocked him to the ground, briefly disarming him. As Zin entered and aimed his weapon at Cole, Cole grabbed hold of Dawson (who retrieved his weapon) before using him as a sheild as Zin fired. The energy blast hit Dawson - killing him. Unintentionally, Dawson's rifle fired - injuring Zin as a bullet hit his shoulder.
Tracker (TV Series) - Episode 13: The Miracle