While it will still take a while before the new season of "Sherlock" returns to TV screens, reports about the season 4 production have begun to circulate online.

On Twitter, production designer Arwel Wyn Jones shared behind-the-scenes photos from the set of "Sherlock" season 4. One of them shows the door bearing the iconic 221B Baker Street address where Sherlock Holmes (Benedict Cumberbatch) and his friend Dr. John Watson (Martin Freeman) live. Jones also shared a photo of the wallpaper that will be used in the filming of "Sherlock" season 4.

This could mean that production for the fourth season of the British crime drama that's based on the best-selling novels by Sir Arthur Conan Doyle could possibly start soon.

In May 2015, Digital Spy reported that series co-creator Steven Moffat confirmed during the BAFTA winners press conference that production for season 4 will begin in spring 2014. He also revealed that the plot for the upcoming season will feature "an emotional upheaval" that could leave fans in awe until the release of the fifth season.

Moffat also told Entertainment Weekly in August 2014 that the fourth season of "Sherlock" will be better than its previous season. "We have a plan to top it. And I do think our plan is devastating. We've practically reduced our cast to tears telling them the plan ... we're probably more excited that we've ever been about Sherlock," the series co-creator shared.

Meanwhile, series co-creator Mark Gatiss also revealed in the same report that they will try to bring the story of "Sherlock" season 4 "somewhere we've never been before." This could mean that the plot will be darker compared to the previous three seasons of the series.

"Sherlock" season 4 is slated to return to BBC sometime in 2017.