Longmire Season 4 Plot and premiere update: Walter to investigate Cady's mother's murder mystery?
Longmire season 4 will premiere on Netflix this summerLongmire/Netflix

Even as Longmire is months away from its season 4 premeire, the cast of the popular crime drama have teased that the upcoming season will be "bigger than ever".

The cast and crew of the American series are currently filming episodes of season 4 in various locations in New Mexico, which will premiere in fall this year.

Veteran actor Terry Camilleri will guest star in the next season of Longmire and the news was confirmed by Adam Bartley, who plays the character of The Ferg in the fan favourite series.

Bartley shared the news on his Instagram account and posted the above image, captioning it "The incredible Terry Camilieri in his #Longmire debut! Better known as Napoleon in Bill and Teds Excellent Adventure!!!"

The actor did not confirm what role Camilieri will be playing, but from the image it appears that he will share screen space with Robert Taylor's Walt Longmire.

Cassidy Freeman, who plays the role of Cady Longmire, the daughter of Walt, told Cartermatt that filming for episodes one and two has been completed, while episodes three and four are being filmed at present.

"We're currently shooting episode 3, and although that seems like its still early, I know it goes by so quickly. Time flies when you're having fun! And although the bones of this show will always be the same: great stories, strong authentic characters, culture, conflict, etc..." she said.

Freeman also teased that the season 4 will be like a 10-hour movie as Netflix will release all episodes at one go.

"Although the fans may not love that they have to wait a little bit longer for the season; it gives us more freedom and lets us craft the season as a 10 hour movie. Netflix is such a cool platform because of this. They are also real excited about the show and eager for us to let us spread our wings. I think the fans will feel fuller episodes ... more organic feeling stories and no commercials!"

The actress has been active on her social media and keeps sharing on-set pictures along with her co-stars.

The series was cancelled by A&E post the season 3 finale, but will now continue on Netflix. There are rumours that season 4 will narrate the mystery behind the murder of Walter's wife and Cady's mother.

The Wyoming county sheriff has maintained her death a well kept secret, so far and claimed that his wife died of cancer, but in the upcoming season Cady may suspect her father's theory and will begin investigating the real reason behind her mother's mysterious death.

Meanwhile, Robert Taylor and Lou Diamond Phillips will return on the show to reprise their roles of Walter and Henry respectively.