In a promotional video for Mount Royal University in Calgary, an interviewer asks student council president Meghan Darcy Melnyk what her fellow students might not guess about her.

"I'm a dork. I play the saxophone. I sing at really random times," Melnyk answered.

How about robbing banks? That didn't come up. But now Melnyk, a 27-year-old communications major who abruptly quit the student presidency in January, is accused in the armed robbery of a Calgary credit union on Wednesday.

Calgary police detective Stu Keown tells ABC News that Melnyk, disguising herself with makeup, sunglasses and a stocking cap, took an undisclosed amount of cash after informing a teller that she had a weapon. According to Keown, Melnyk made her getaway in a PT Cruiser with her German shepherd.

A credit union employee wrote down her license plate, and a police helicopter spotted her car a short time later. Police caught up with Melnyk in traffic. In her car, police discovered a knife they believe was used in the robbery.

But Meghan Melnyk may have kept more secrets from her fellow students. Calgary police tell ABC News she also had outstanding arrest warrants for fraud, forgery and violating probation after being found in possession of a stolen car. At the time of her resignation as student president, Melnyk told the Mount Royal student newspaper that she loved her job, "but I'm just at that point where I've given so much of myself that I'm very much burnt out."

The Melnyk case is "highly unusual," said Keown, adding that most bank robbers in his region tend to be supporting drug habits. But police remain puzzled by Melnyk's motive since she refused to cooperate after her arrest.

Melnyk's former colleagues on the students' association seem stunned yet sympathetic. Vice president Michelle Dennis told ABC News, "We are as shocked as everyone else. We certainly have no idea why she chose to act in this way. We do hope that she gets the help and support that she needs."

Melnyk remains in custody pending a bail hearing.