Sayer was born October 18, 1799, "[t]he natural son of John Sayer of the parish of Sainte Anne," and an
Ojibway woman, Marguerite. Records from
Pointe-Claire, Quebec, indicate that he was baptized on July 21, 1815. Sayer enlisted as a
coureur des bois with the McTavish, McGillivray & Company on April 7, 1818, as was registered by the notary J.-G. Beek at
Ste Anne, Bout de l'Isle, in the west of the
Island of Montreal. He was hired to work in the areas controlled by the
North West Company. The contract is preserved in the Archives Nationales du Quebec. According to the Hudson Bay Archives, Pierre Guillaume worked for the North West Company at
Cumberland House from 1818 to 1821, the year of the union of the North West and Hudson Bay companies. From 1828 to 1829, he worked for the Hudson Bay Company as a Bowsman at
Fort Pelly in the Swan River District and then stayed on as a Steersman from 1829 to 1832. In 1832, he was freed from his service in the Hudson Bay Company and moved to Grantown, near the
Red River Settlement. On March 2, 1835, according to the St. Francois Xavier Catholic Church marriage records, Sayer married Josephte Frobisher, the elder daughter of fur trader Alexander Frobisher and his
Cree wife, on March 2, 1835, at St. Francois Xavier. Josephte, who was born around 1795 to 1807, was baptized the same day as the wedding. She and Sayer had eight sons and four daughters together. ==Trial==