Valerie Daniels (Janet Zarish) is the main villainess from "Secret Arrangements," episode 4.19 of Blue Bloods (airdate April 11, 2014).
Valerie Daniels is a professor and the wife of fellow professor Benjamin Daniels, who was found shot to death in his car, with his wallet and watch missing but with two cell phones in his possession. The phones bewildered detectives Danny Reagan and Maria Baez, and during their interview with Valerie inside her apartment, Valerie spoke fondly of her husband; responding to Danny's questions about the phones and any possible suspect activity Benjamin was involved in by stating that her husband wouldn't be involved in anything remotely criminal, before she was set to phone her daughter about Benjamin.
The investigation revealed that Benjamin had some connection to a scholarship program that was suspected of being a front for a prostitution ring, and it was later revealed that Benjamin was having an extramarital affair with 20-year-old student Maggie Parker, who was interviewed by the detectives. Maggie stated that her ex-boyfriend, Milo Finley, found out and became angry enough to want Benjamin killed, leading to Milo being suspected. However, Milo revealed that he was drunk at a bar on the night of the murder, and after a return to the apartment building, where it was revealed that a possible suspect could have used the key to the emergency exit, suspicion turned to Valerie. The suspicion increased when Danny, Maria, and Lt. Sid Gormley found out that Benjamin was spending a plethora of money on Maggie, and he wrote various love poems to her as well.
As also revealed, one of the poems to Maggie had an outdated reference to the use of a subway token, which revealed that Benjamin had used the same poem he wrote to Valerie years ago to express his love for his mistress. Out of anger over the affair, and even more so over Benjamin using what she considered "her words" to woo another woman, Valerie turned heel and shot Benjamin to death while he was parked in front of the school. The villainess was confronted by the pair of detectives about the affair and the fact that Benjamin had recycled his old poems to his wife and gave them to Maggie, with Valerie denying her husband's infidelity. However, when Danny stated that Benjamin was looking to replace his wife, the evil Valerie shouted that she "couldn't let that happen," revealing her scorned heel persona before her off-screen arrest for her husband's murder.