The line I’d heard on Monster, a drama based on the life of Florida serial killer Aileen “Lee” Wuornos, was that while Charlize Theron’s work in the lead role was truly stunning, the movie itself was pretty unremarkable. The first part of that judgment I have no trouble endorsing: Theron’s bravura turn is little short of historic, and will almost certainly win this year’s Best Actress Oscar. Yet Monster itself, far from being just a mere frame for this startling tour de force, is a surprisingly searching and complex work that marks a formidable debut for its 31-year-old writer-director, Patty Jenkins.

Wuornos, who was executed in 2002, confessed to killing seven men while working as what she called a “hitchhiking hooker” along Florida’s I-75 in 1989-90. Though she was all over the tabloids and shows like Hard Copy at the time of her trials, I first encountered her in Nick Broomfield’s 1992 documentary Aileen Wuornos: The Selling of a Serial Killer, which focused on the media circus surrounding the case and the indications that Wuornos was exploited by her pot-head attorney, born-again Christian adopted mother and several cops, who all conspired to sell the story of “America’s first female serial killer” to Hollywood. Given the sensational atmosphere, Broomfield’s interest in Wuornos’ trajectory through the courts and the public eye was understandable.

And indeed, it’s a story unto itself. The one Monster sets out to tell, in contrast, is the story of what occurred in the year or so prior to Wuornos’ arrest, the year of the murders. The film begins with some glancing, impressionistic views of what was, in fact, an astonishingly awful childhood: Abandoned as an infant by her mother after her father committed suicide, Wuornos was raised by an abusive grandfather who threw her out after she got pregnant at age 13, forcing her to live al fresco in the Michigan woods in winter.

Looking for various sorts of warmth, she made her way to Florida, and two decades later was still living by petty crime and hooking when she met Tyria Moore in a gay bar. By most accounts, Moore was a lesbian and Wuornos a de facto bisexual who had plenty of reasons to be fed up with men. The two became a couple and remained so for three years, until Moore crumbled under police pressure and gave evidence against Wuornos. For Wuornos, this was merely the latest in a lifetime of betrayals, but it was arguably the worst; she thereafter never ceased to maintain that Moore was the love of her life.

I will admit that, knowing something of the case, I was a bit suspicious of Monster in its initial sections. In the movie, the Moore character is called Selby and is set at a notable fictional distance from her real-life prototype. Where in documentary footage Moore comes across as foursquare, middle-aged and decidedly butch, Selby, as played by Christina Ricci, is young, dewy and doe-eyed. That Monster starts off with a tight focus on her and Wuornos’ relationship makes this a love story from the get-go, and that in turn threatens to romanticize–and thereby, perhaps, to excuse–Wuornos’ eventual turn to murder.

Yet that’s not what happens, and I later decided that Jenkins’ opening tack, which shows us Wuornos as human enough to love, was an intelligent and fitting way of addressing both the murky facts of the case and the challenges of formulating those into a responsible, insightful drama. With a subject as tricky as Monster‘s, those aspects deserve separate consideration.

First, concerning the facts. Wuornos initially claimed that she killed all seven men in self-defense; that each one had attacked her and she responded as she had to save her skin. (When prosecutors objected that such a claim might be believable in a single case but hardly in a string of seven, Wuornos responded, quite logically, that number had nothing to do with the principle of self-defense.) Much later, after she had been convicted in six of the cases and sentenced to death with virtually no hope of reprieve, she claimed she wanted to die and reversed her story, saying that she’d killed all seven in cold blood.

A nuanced view of the case suggests that the truth lies somewhere in between: that Wuornos was in fact brutally raped by the first of her victims (a man who’d spent years in confinement for sexual violence, a fact not introduced at her trial) and that, once she’d killed, she found it easy to repeat the crime, spurred on not only by her vast stores of pent-up rage, but also by the desire for money that would help keep Moore by her side. This is the story that Monster tells, which presupposes that Wuornos wasn’t a monster–an irretrievable psychopath–when she first pulled the trigger, but that she became one as she kept pulling it again and again.

Indeed, this slide into moral delirium has a believable gradualness as Jenkins stages it. After the torturous attack that results in the first killing, Wuornos’ second murder takes the life of a man who’s simply full of rough swagger. Then she picks up a stuttering novice who’s simply too meek a target; she services him manually and lets him go. That act of mercy aside, her malice develops its own terrible momentum. By the end she’s killing a man who only offered her help and is on his knees begging for his life.

Beyond its credibility in terms of both the facts and human psychology, Jenkins’ reading cannily steers between the iconic extremes of the case’s public career. As soon as Wuornos became a celebrity criminal, she was seen by different constituencies as either a man-hating lesbian psycho or a righteously vengeful feminist heroine. (Coincidentally, 1991, the year of Wuornos’ arrest, also brought us Thelma and Louise.) Both such views of course depend on the voyeuristic distance and kneejerk reductivism characteristic of American media culture, and their dangerous simplifications are precisely what the artistic nuance and complexity of Monster so strikingly combat.

Jenkins’ great triumph, it seems to me, lies in that scrupulous richness, which will disappoint only those who cling to the most Manichean notions of good/evil, right/wrong. To show that Wuornos was human–was catapulted toward her crimes by a lifetime of abuse, and perhaps by one assault in particular–in no way implies that she was not a monster once she let self-defense curdle into vengeful cruelty; in fact, it only makes her tragedy that much more universal. One of the movie’s canniest touches involves a Vietnam vet (Bruce Dern) who’s friendly with Wuornos and at one point draws a parallel between their fates. The comparison eerily recalls a recent news story about the Phoenix program of U.S. atrocities in Vietnam which quoted one of the unprosecuted perpetrators as defending himself by saying, “I was just trying to survive.” No doubt Wuornos would say the same: the moral inversion that permits murder begins in such self-deception.

If Patty Jenkins provides a compelling conceptualization of Wuornos’ story, Charlize Theron embodies it in a way that’s flat-out amazing. Having gained 20-30 pounds for the role, and been augmented with prosthetic teeth and a makeup job that uncannily duplicates Wuornos’ pasty, freckled skin, the actress proceeds to recreate the killer’s distinctive repertoire of mannerisms, the downward-pulling mouth and flaring nostrils, the rolling shoulders and thrown-back head and bulging eyes, the lunging posture and explosive laugh. Yet this is no mere mimicry, because its real force comes from within. Wuornos’ vulnerability and rage, her hard-won pride and hair-trigger volatility are all evident in this incandescent performance, which easily equals Robert De Niro’s celebrated self-transformation in Raging Bull.

Viewers wanting to know more about this case’s facts, or to assay the phenomenal veracity of Theron’s work, should seek out Aileen Wuornos: The Selling of a Serial Killer or wait for a local appearance of Nick Broomfield’s second and final film on the subject, Aileen: Life and Death of a Serial Killer, which opened in New York and L.A. on Jan. 9.

The new documentary, which is notably superior to its predecessor, begins with Wuornos’ final appeals the year before her execution (Broomfield is called to the stand to testify about her original lawyer’s habit of smoking seven joints on the way to interview her in prison), doubles back to interview childhood cronies about her harsh early life, then watches as Florida Gov. Jeb Bush, who’s up for reelection in an execution-hungry state, declines to stay her execution after three state-appointed shrinks take all of 15 minutes to declare her sane and thus ready for the lethal injection. Because Wuornos’ final interview, which she grants Broomfield the day before her execution, indicates that she’s clearly lost touch with reality, the glum filmmaker understandably wonders what one would have to do to be declared insane.

I have a feeling that Broomfield’s latest will be a substantial indie-level hit, and I’d urge Triangle art houses to book it forthwith. Indeed, it and Monster ideally should be shown together, since it’s the documentary that gives us Wuornos’ final words to any camera, hurled with her characteristic mix of snarl and self-exculpation: “Thanks a lot, society, for railroading my ass.” EndBlock