Tough gravelly voiced Al Pacino and Robert De Niro, playing NYPD detectives, are the selling point for Righteous Kill, another entry in the cop-buddies vs. serial-killer category. However, the movie is also about two men’s brotherhood of love and trust that stands in for family or other ties.

Thinking of these central “equally matched” characters without particular actors in mind, scriptwriter Russell Gewirtz worked backwards from the ending, the fashionable “twist” that upsets appearances up to there. A flow of self-righteous gunnings-down of lowlifes emerges as the work of some insider, although no tabloid or citizen awareness is hinted; amidst animosities among officers, the suspicion grows that the psychopath is one of their own. Withholding wider context, the film opens with, and returns to, a surveillance camera “confession” that pinpoints the culprit but, obviously, does not; the two leads called by nicknames, the viewer needs to know the ending before he can take in the proper name from that black-and-white video tape.

Both past sixty-five, thin-faced Pacino and sleekly rounder De Niro only seem in memory to have coincided somewhere -- no joint scenes in The Godfather Part II, minutes together in Heat -- and despite distinctions in their Righteous Kill personalities, calmly ironic against volatile obscene, the two actors do not strain. Are they walking through by being their ethnic selves, or else great actors effortlessly living in others’ screen skins?

Their Detectives First Grade synergize each other, De Niro as Tom “Turk” Cowan and Pacino’s David “Rooster” Fish. The latter is furnished no outside personal life apart from rooting on his partner in interdepartmental baseball. Like him, having seen urban years of depravity and injustice and shot people dead, Turk coaches a girls’ ball team and is a widower with an afterthought grown daughter in California and a touchy connection with Karen Corelli (Carla Gugino) of the crime scene unit, who likes her men sadistic in the sack.

Now and again Rooster and Turk spill a few beans about boyhood neighborhoods, churches and TV shows, but their address-less existence is hermetic, sealed even, or especially, against detective pair on-the-make Simon Perez and Teddie Riley (John Leguizamo, Donnie Wahlberg). Resentful at the veterans’ sarcastic superiority and an earlier internal affairs conflict, and Perez eyeing the affair with Karen, these younger officers push suspicion in the direction of Turk.

That hothead uses no tact to sidestep the imputation, even as he and Rooster are obliged into sessions with a departmental shrink, for these two are cut in the Dirty Harry mold of lawman who step beyond legal bounds. Nasty pimp Rambo (Rob Dyrdek) is killed as is a gun runner, an unconvicted child rapist, Catholic Fr. Connell, and other victims who are dismissed as garbage criminal perverts in the killer’s rhymed calling cards.

SPOILER ALERT

A disgraced former cop (Alan Blumenfeld) gets crossed off the list, and Russian Mafia goon Mugalat (Oleg Taktarov) survives three bullets added to three more from before but lies comatose in St. Luke’s Hospital. The circle narrows. After a previous botched sting that ended in beatings and death, the heroes turn once again to Harlem Club 404 owner and drug dealer Spider (Curtis Jackson/50 Cent).

The killer communicates that fourteen bodies will end it -- double Se7en? Despite police success after a fashion, that death foretold will ironically take place, to be covered up and “the door closed.” Ironic, too, is that criminals now can breathe more easily among unaware Manhattanites.

Sensed, anticipated and in any case advertised, the unexpected twist is expected. Moviegoer instinct knows that clues and fingers point all along to the wrong person. Sherlock Holmes stressed that after eliminating the impossible, the answer is the improbability that remains. Although moved by the presence of its partner-leads, Righteous Kill does not make for edge-of-the-seat suspense until the very end, as masterful films do. 

(Released by Overture Films and rated “R” for violence, pervasive language and some sexuality and brief drug use.)