The Fall of the House of Usher: How did Roderick find out that Mr. Griswold forged signatures?

In the episode "The Black Cat" of The Fall of the House of Usher, Roderick Usher discovers some shocking information about his boss, Mr. Griswold. Roderick learns that his signature was forged on papers related to problematic clinical trials conducted by Fortunato Pharmaceuticals. Despite his initial confrontation with Mr. Griswold, Roderick is convinced to let the issue slide and continue supporting the company's goals.However, Roderick's wife, Annabel, is not impressed and urges him to do the right thing by exposing Fortunato's corruption and resigning from his job. On the other hand, Roderick's sister, Madeline, sees an opportunity to gain control of the company by using an investigator named Dupin. Madeline wants Roderick to work with Dupin to bring down Griswold and seize control of the pharmaceutical company founded by their father.In the present day, Roderick's family is dealing with the aftermath of his sister Camille's death and trying to unravel the mysteries surrounding her demise. Roderick becomes suspicious of a new experiment conducted by Victorine and suspects that it may be related to Camille's investigation into the company. Despite his declining mental health due to vascular dementia, Roderick is excited about the experiment and momentarily forgets the circumstances of Camille's death.A significant development occurs when Roderick and Madeline recognize a woman, Verna, from their past. They receive an image from Arthur Pym showing Verna at the laboratory's front desk on the night Camille was killed. This raises a red flag for the siblings, and Madeline attempts to revisit the bar where they first met Verna, only to find it closed with an ominous raven nearby.Meanwhile, Leo, another Usher sibling, experiences a downward spiral of paranoia after unknowingly killing his boyfriend's pet cat. He obtains a new cat to replace the deceased one, but it displays disturbing behavior, scratching Leo and leaving dead animals around the house. Leo's mental state deteriorates, and he becomes convinced that the cat is residing within the walls. His paranoia culminates with him chasing the cat and falling to his death, leaving his ex-boyfriend Julius shocked and frightened.Ultimately, Roderick starts to realize that the deaths of his loved ones may not be coincidental and that there may be a deeper conspiracy at play. With the revelations about his boss and the connection to Verna, Roderick is beginning to understand that there is more to Fortunato Pharmaceuticals than meets the eye.In conclusion, Roderick Usher discovers that his boss, Mr. Griswold, had forged his signature on papers related to problematic clinical trials. This discovery, along with the introduction of Verna and the mysteries surrounding Camille's death, hints at a deeper conspiracy within Fortunato Pharmaceuticals. As Roderick delves further into the truth, he becomes more aware that the deaths within his family may be part of a larger scheme.