Dina Lopez (Rosie Garcia) is the main villainess from The Closer's fifth season opener, "Products of Discovery" (airdate June 8, 2009). She is the girlfriend of notorious drug dealer, Tavio Galan.
Dina was first shown in surveillance video speaking to Galan while visiting him in prison, as it was part of Major Crimes' investigation into the murder of four family members inside their home. Major Crimes's Louie Provenza's statement that he went to the wrong house on the wrong thoroughfare led Brenda Leigh Johnson to discover the killer did the same thing due to a typographical error. This was confirmed when the correct house turned out to be the home of a witness testifying against Galan. Regarding Dina and Galan's conversation, it had Galan asking Dina to help him find the witness, with Dina agreeing to do so.
After a batch of candy bars were found, they were revealed to be for sale to raise money for a high school that was attended by Dina's half-sister, which revealed Dina as the murderess. Brenda and the rest of Major Crimes intercepted Dina's meeting with Galan, and it was at this point where everything was revealed. During the conversation, Dina was given the witness' address: 214 26th Place, but she actually went to 214 26th Street, which is where the family of Victor Garcia lived. She went to the house under the pretense of selling candy bars, taking the box belonging to her half-sister, which led to Dina being admitted to the house. Once she entered, Dina shot all four family members to death: Victor's wife Cynthia, their young children Miguel and Lucia, and Cynthia's mother Diana -- covering their faces before shooting them.
Dina denied everything to Brenda, who later breathed into the glass and revealed that Galan had written the address during their conversation but Dina went to the wrong address. At that moment, Dina confessed, stating that she committed the murders out of love for Galan and that she wanted to maintain their family, as she was pregnant with his baby. In response, Brenda chided Dina for killing a family to make sure she had one of her own, and she was later handcuffed and arrested.