Roberto Ramos is a janitor of several apartment buildings and was a suspect of the murder of Virginia Boone, the tenant of one of the buildings he worked at.
History
At some point Roberto managed to immigrate to America despite not having papers to be able to do so. Robert married a woman and had a daughter. Roberto ended up becoming a janitor for several buildings. Also at some point Roberto was given five thousand dollars by Virgina Boone, Roberto said that she didnt have to give him that much money but she insisted.
While cleaning an alley, Roberto was confronted by Detectives Briscoe and Green about the murder of Virginia. Roberto tells the detectives that he saw a "not so old white man" at the time of Virginia's murder but he couldn't remember what he was wearing. Detective Briscoe tells Roberto if he remembered what the man was wearing to call him. Roberto, believing that the detectives were going to figure out that he was an illegal immigrant told them he had a family emergency so he could lay low.
However, the detectives, believing Roberto to have been the one to have killed Virginia managed to get to the house of the man Roberto was staying at and arrested Roberto. And find that Roberto has a knife he uses for his job.
Roberto was brought to an interrogation room where he explained to the detectives that he believed he was going to be discovered as an illegal immigrant and how he didn't want to be arrested. Detective Green says that they don't care that he is an illegal immigrant. Roberto tells the detectives that he cried for Virgina when she died but Detective Briscoe tells him that they will find blood on his knife if he did kill Virginia.
However, when Roberto's knife was examined, Dr. Rodgers determined that there was no trace of Virginia's blood as well as the knife not being long enough to cause the wounds in Virginia's chest, proving that Roberto was innocent of Virgina's murder. ROberto was then released from police custody after being proven innocent. (L&O: "Possession")