“We’ve banged ourselves, getting cuts and scrapes. I have calluses on my wrists from crawling under the piano,” says actor Joe Kinosian. “And we’ve had to have maintenance on everything—like the furniture, because of flinging it around.”

The two-hander that sends Kinosian, 30, into such frantic kinetic overdrive is Murder for Two—A Killer Musical at Chicago Shakes (recently extended, for a third time, through October 16). Since he plays all nine suspects, it would be strange if this murder mystery didn’t send him careening around the stage. And, more to the point, his face careening into different shapes in a virtuoso performance.

Moment by moment, he captures each of his characters—who range from the dead man’s widow, Dahlia, to gruff old Dr. Griff to a crazy ballerina a la Black Swan to a small boy. Alan Schmuckler, playing the de facto detective, represents the story’s tiny smidgen of sanity. Both men play the piano and sing, and Kinosian wrote the music and the book—a task he shared with co-creator/lyricist Kellen Blair, 27.

The play has a checkered past. Since it’s been workshopped over the past couple years in other cities, Kinosian has had the chance to redefine his babies—the characters he’s both written and plays. “The longest run previous to this was three weeks,” he says. “In those runs, my favorite character was the widow, with all her ridiculous non sequiturs and Marx Brothers punch lines. But as we’ve run this show so long, different characters are becoming the focus. Audiences now are really into the ballerina, and in another few weeks, it might be someone else.”

“I love doing the physicality of the widow, with her bum hip and everything. I had specific sources, but I’m not gonna tell you! … But the voice is an old friend’s mother, and the walk is from a roommate of mine who was in an accident. In our defense, I do think she has taken on a life of her own beyond her inspirations.”

One thing Kinosian and Blair have discovered is that making these farcical characters a little more vulnerable and human has improved them. “With Dahlia, we started out very irreverent,” says Kinosian. “Then we said, ‘What if she was a dancer too, married a guy who made her stop working, had the debilitating hip thing, and was left with no outlet for her creativity?’ The worse off we made her, the funnier she got.”

The psychiatrist, Dr. Griff, has also changed over time. “He was a former drill sergeant, then a preppy tennis player, and at one point he was a leprechaun or fairy,” says Kinosian. “Then he morphed into his current character, where the gimmick is that he wants a friend. His scenes died until we formed this notion and wrote the song for him [“A Friend Like You”] at the 11th hour.”

A native of Wauwatosa, Wisconsin, Kinosian now lives in New York—and says his favorite show of all time is Tracy Letts’s anti-farce August: Osage County. “Back when I had no money to buy groceries, I paid to see it six times on Broadway.” Though he hasn’t had much opportunityto go to Chicago theater, Kinosian says, he loves the supportive community here.

Kinosian and Blair are working on a new musical (“a soap-opera concept with librarians in a small Midwestern children’s library”) and exploring other options for Murder for Two. But “we want to ride this out in Chicago,” Kinosian says. “Our best-case scenario was to run through the summer—so this is fantastic!”