TORONTO -- The head of the prison in which a troubled teen killed herself denied on Monday knowing of the paralyzing confusion among guards about when to enter her cell to save her.

Testifying at the inquest into Ashley Smith's death, Cindy Berry said guards were to stay outside unless Smith was in "medical distress."

"If she wasn't breathing, she wasn't responding, she was losing consciousness," Berry said.

"The officers would have to assess that."

The inquest has heard how guards, believing Smith to be in grave danger, would rush in and cut ligatures off her neck.

However, they were frequently disciplined for making that call -- at Berry's behest -- even in cases where Smith's face had turned purple and she struggled for breath.

"Use your discretion, experience and training to assess the situation and to act accordingly," Berry said she told guards when asked directly.

"I understand now that it could have been a conflict."

Smith, 19, of Moncton, N.B., choked herself to death on Oct. 19, 2007, as officers videotaped her but did not intervene until it was too late.

The former acting warden at Grand Valley Institution in Kitchener, Ont., denied knowing they had been warned to stay out of Smith's segregation cell until she stopped breathing.

In retrospect, she said, Smith didn't belong at Grand Valley, which was poorly equipped to deal with her.

"I don't believe the use-of-force model is appropriate for people with behaviours such as Ashley," Berry said.

The teen had been moved to the facility at the end of August 2007 from her "home" prison in Truro, N.S. It was meant to be a three-week stay to give exhausted staff there a break.

Smith began acting out immediately on arrival.

Under close scrutiny from regional and national headquarters, Grand Valley developed a "management plan" that involved acting coldly toward her if she misbehaved.

At one point Smith appeared to respond, and was moved from the segregation range for a few days.

The move ended badly. Smith smashed the TV in her cell and was sent back to isolation. Her behaviour deteriorated markedly.

"She was more disruptive," Berry said. "GVI was not able to manage Ashley at all."

On Oct. 2, Berry asked the prison's former warden, Brinda Wilson-Demuth, who had been promoted to a senior position in Ottawa, to move Smith back to Nova as was originally planned. The answer was no.

"She just said, 'You're doing a good job'."

Berry testified she had been cajoled into taking on the warden role at Grand Valley -- she prefers dealing with men -- for four months.

She said she found a short-staffed prison with top management in disarray when she started in mid-August 2007, two weeks before Smith's arrival.

Only one senior manager was in a permanent position: deputy warden Joanna Pauline, who higher-ups deemed a "poor leader" and totally incompetent, Berry said.

Pauline testified last week she filed a harassment complaint against Berry.

The inquest heard management plans were based on psychologist input that indicated Smith was "intent on playing games" rather than suffering from a mental illness.

The plans were all sent up the Correctional Service of Canada ladder for scrutiny -- something Berry called extraordinary.

She got almost no feedback, and assumed that meant the plans "met with their approval."

Also Monday, the federal prison ombudsman said self-injury incidents in federal penitentiaries have more than tripled since Smith died.

The report called on the prison service to treat chronic self-injury primarily as a mental-health concern, not a security or control issue.

Berry faces further cross-examination Tuesday.