Rona Mark knows Pittsburghers can be sticklers about geography, but she hopes they'll give her a break when they see how she's redrawn the city map -- just a bit -- for "Strange Girls."

"I swear, I did the best I could," the writer-director said in a phone call earlier this week from New York. After all, she graduated from Upper St. Clair High School, but she was working with a budget of just $125,000, which she had to beg, borrow and charge on credit cards for her movie about identical twin sisters.

They do everything together -- including murder.

"Strange Girls" will have its world premiere Friday at 7:30 p.m. at Pittsburgh Filmmakers' Melwood Screening Room. The movie repeats Saturday at 3 p.m., also at Melwood.

Mark considers "Strange Girls" a "perverted coming-of-age story." She used to call it a horror movie but says, "In the current climate, it doesn't seem to be one. It's not quite torture porn and there aren't a lot of scares per minute," but it does contain frightening and adult moments.

Asked how she came up with the idea, the filmmaker said, "I always had an interest in true crime, and there was a book I had read about these twin sisters in England who became arsonists.

"So a lot of the inspiration came from those twins, plus some other kooky twin true-crime stories I had read," including how a 22-year-old Korean woman conspired to kill her identical twin in California in 1996.

"Strange Girls" marks the first feature-length film for Mark, who returns to Pittsburgh regularly to visit her father, Gunther Mark, in Upper St. Clair.

After high school, she went to Israel, worked on a kibbutz, earned a bachelor's degree and did a year of film studies in Tel Aviv. But she realized if she wanted to make films, she should return to the States and received a master's in fine arts (concentration in film directing) from Columbia University.

She filmed "Strange Girls" in such locations as New Kensington, where a hospital doubled for the Mayfield Psychiatric Institute, along with Swissvale, Bloomfield, Polish Hill and Connellsville. Due to a lack of money, she shot in two two-week blocks, in September 2005 and March 2006.

"I can't believe I went into production without the money to finish it," and she would not recommend such risky, ill-advised behavior.

As for the uncomfortable task of asking people for money and tapping her credit cards, she says, "Waiting around for Hollywood people to give you money to produce a film is like trying to win the lottery, and I've been down that road many times, and you get to a point where, 'Wow, I think I'm going to have to do this myself.' "

Although her leading ladies, Angela and Jordana Berliner, have curly red hair, that wasn't a prerequisite. "I figured if I can find twins who are really good actors, I'd take them how I can get them. I didn't have red hair in the script, but it was definitely a boon," since it makes the women stand out.

The identical sisters, members of an L.A. theater troupe, were fine with the film's content.

"Angela's a playwright, as well, and Jordana's a starving actress. They loved it" and embraced the twin tussles in the story. And while Mark couldn't tell the women apart when she first met them, she says, "Now, they're really different to me, of course."

The cast also includes actress Adrienne Wehr, producer of "The Bread, My Sweet," as a therapist who inherits the case of the twins after taking over the staff at Mayfield. "She just showed up for the casting call. Boy, what a bit of luck that was."

Mark also drew on local actors or former locals who can still do a mean Pittsburgh accent. "I hope they appreciate the accent. In 'Deer Hunter,' they all had Brooklyn accents."

Mark and the Berliner twins are scheduled to appear at the Friday premiere.