SANTA CLARA, Calif. -- Katie Sowers, one of the NFL's first full-time female assistants and its first openly gay coach, will not return to the San Francisco 49ers next season, a league source confirmed Thursday.

After four years with the team, Sowers and the Niners are parting ways as her contract expires, the source told ESPN. The Bay Area News Group first reported Sowers' departure.

Sowers spent her time with the team as an offensive assistant, primarily working alongside receivers coach Wes Welker with that position group.

In an Instagram photo posted earlier this week, Sowers captioned a photo of herself with, "I don't know what 2021 has in store ... but I promise you, it won't be boring."

After spending the 2016 season as an intern with the Atlanta Falcons, Sowers joined the 49ers as part of their 2017 Bill Walsh NFL Coaching Diversity Fellowship. At the conclusion of that program, the team retained her as a seasonal offensive assistant.

For the past three seasons, Sowers, 34, has served as an offensive assistant, making her the franchise's first full-time female coach and the second full-time female assistant coach in league history.

While her role with the Niners mostly had her working with receivers, she also had a hand in game preparation with all offensive skill players.

In February, Sowers became the first female member of an NFL staff to coach in a Super Bowl.

"Being the first female in the Super Bowl, it's surreal," Sowers said then. "It really is. But what I want to continue to say is that even though I'm the first, the most important thing is I'm not the last and we continue to grow it."