Season /Series Finale Question (Spoilers)

It was horrible that Maureen got shot and died but i thought it was implied that they was a corrupt link in the DA offices as how they did know Maureen and the Detective were going to the apartment i did think it maybe Conlon or the cop Matt. Anyone else think this?

FYC Oscars 2008 Reservation Road
Best Actress Catherine Keener - An American Crime