When the long-running police procedural drama television series returns to CBS for its 13th season later this fall, fans are expected to see some major changes, particularly to the series' characters.

According to Christian Today, one particular character who is expected to experience major changes in the upcoming season is Leroy Jethro Gibbs (Mark Harmon), who fans saw being shot in the Season 12 finale.

While Gibbs is struggling for his life, it will certainly reawaken the entire Naval Criminal Investigative Service (NCIS) team. The premiere episode of 'NCIS' Season 13, which airs on Sept. 22, will open with Gibbs seen aboard the Navy hospital ship in a critical state and undergoing treatment.

Meanwhile, Tony DiNozzo (Michael Weatherly) and the CIA officer Joanna Teague (Mimi Rogers) will be seen heading to Shanghai to go all-out for the terrorist group called The Calling.

In a recent interview with TV Fanatic, 'NCIS' show runner Gary Glasberg hinted at what fans may expect in the upcoming season.

According to Glasberg, having healed his wounds, Gibbs will return as a changed man. As Gibbs won't be fit enough to manage the team the task would be left to DiNozzo, who will now be in-charge, resulting in some tension between him and Gibbs.

Glasberg further shared, "That's one of the big character arcs that we're going to get into this season. Gibbs and Tony are really going to feel some tension between the two of them."

In fact, 'NCIS' is known to eliminate its major characters as the show progresses and one of them that shocked many fans was the exit of Cote de Pablo's character Ziva David, who played a major role in the series for eight years before she said goodbye in Season 11.

Since her story was rushed, it did not give fans the ending they wanted. Nevertheless, there are reports that de Pablo may return in Season 13 and reprise her character.

A report in TV Line (via Design&Trend) stated that Weatherly teased about Ziva's return saying, "I have come to understand that there will be, later in the year, some guest stars that will melt the avid 'NCIS' viewer's brain."

This statement has led fans to speculate and hope that Weatherly was referring to Ziva.

TVLine reported that in January, de Pablo expressed her opinion about her character's exit from the show, and she agrees that her storyline was rushed. However, de Pablo said that there was a possibility that she could return to the show sometime.

"Under the right circumstances, I think it could definitely be explored," she said.

'NCIS' Season 13 premieres on CBS on Sept. 22.