This Texan right-hander pitched his entire college career in New Mexico, with the final three of five seasons at New Mexico State. Jefferson went undrafted and pitched for the Trenton Thunder and Billings Mustangs in 2021 before signing a contract with the Seattle Mariners in late August. 

He began 2022 at triple-A Tacoma but primarily pitched at low-A Modesto. 2023 was also mostly in Modesto for Jefferson, but he did make an appearance at both low-A Everett and double-A Arkansas. 2024 started and was mostly with the Everrett AquaSox, but Jefferson made two stints with the Tacoma Rainiers. Seattle released Jefferson this spring but impressed in a bullpen to lead to the Lake Country DockHounds.