Rosa Escobar and her unnamed fellow inmates are unseen villainesses from Blue Bloods' third season finale, "This Way Out" (airdate May 10, 2013).
Rosa Escobar, as mentioned by detective Danny Reagan, was an inmate at a prison where Nona Palmeira was locked up for drug possession--a crime committed by Santana (Nona's lover and the leader of the Los Lordes gang), with Nona caught with the drugs and arrested in Santana's place. Danny later made attempts to get Nona moved to protective custody, only to learn that Nona was stabbed twice in lockup (she survived).
As Nona herself revealed, four women committed the attack, with Danny revealing one of them as Rosa Escobar, who received a call from Santana to "take care" of Nona. Afterwards, the evil Rosa and three other inmates attacked Nona, with the guards looking the other way. The episode ended with Los Lordes being taken down and arrested one by one, including Santana, while Nona was given a chance at a new life--as Danny promised. Rosa and her evil cohorts' fate wasn't revealed, though it can be assumed that they received additional jail time for their attack on Nona.