There's still a mystery to the identity of Alexander Kirk (Ulrich Thomsen), who was introduced in season 3 of "The Blacklist." In the upcoming season, however, the mysterious character and his connection to Liz (Megan Boone) will be exposed.

In the season 3 finale, Alexander revealed to Liz that he is her father. Red (James Spader), on the other hand, thinks that Alexander may have a hidden agenda for telling Liz about the blood relation that they have. Red also insists that Alexander is not Liz's real father.

But now that Alexander has come out with this big revelation, it remains to be seen if he can be trusted. After all, he did abduct Liz and her daughter with Tom (Ryan Eggold), Agnes.

But show executive producers Jon Bokenkamp and John Eisendrath might just have the answer. In an earlier interview with Entertainment Weekly, Eisendrath only teased that fans have yet to know if Alexander is really trustworthy. "He says he's her father, but is he going to hurt her, help her, be kind to her, or does he want to destroy her?" he said.

This should be a big mystery saved up for season 4. What's certain is that Alexander's connection with Liz should give a clearer understanding about Liz' relationship with Red, Bokenkamp assured.

Meanwhile, Liz, who has now found out about her father, fears for the life of her family. Considering she was abducted by the very person who claims to be her father, she might need to be rescued. Red will track down Alexander's hideout and will save Liz, but will not deny the betrayal he felt after finding out that Liz faked her death all along.

Besides Liz's connection to Alexander and Red, her "twisted past" will also be given focus in season 4, TV Guide reported. At the same time, she will also need to come to terms with the fact that Alexander is her father.

'The Blacklist' season 4 returns to NBC on Sept. 22.