Shera had just returned from CT Corporation after working overtime when she came across such a huge scoop. Who would have thought that Carlos' and Alexa's relationship had advanced so fast? She seemed to have let down her guard around him as well.
What was more sensational, his feelings for her were real. When she took her DNA sample from him, she obviously noticed his reluctance. He was conflicted between protecting her trust and fulfilling his duty.
Actually, she was reluctant too. She knew that Alexa would be upset about this, but she also knew that if she didn't find the answers to all the questions she had, she would never be able to calm down. It was probably because she knew that trouble was brewing and therefore paranoid of everything. She also knew that Alexa would rather die than tell her the truth, which was why she had chosen this method.