The report, entered as evidence at the Ashley Smith inquest, also concluded that John Tarala ordered subordinates to falsify their accounts of the incidents.
The document, finalized in July 2007, followed an investigation into complaints Smith had made against Tarala, a supervising guard at the Regional Psychiatric Centre in Saskatoon.
Janet-Sue Hamilton, longtime warden of the Edmonton Institution for Women, chaired the three-member investigative team that probed Smith's assault complaints.
In the first incident on March 14, 2013, Smith complained Tarala had stepped on her head after staff entered her segregation cell to cut a ligature from her neck.
An officer who saw the incident later described Tarala's actions to a registered nurse as a "J.T. special," but the witness officers all refused to provide such information to investigators, according to the report.
However, the investigators deemed the registered nurse, Sindee Tchorzewski, to be a "credible witness" with a "clear and detailed" recollection of events.
"Tchorzewski had nothing to gain in bringing these allegations forward," the report concluded.
"In fact, she has suffered financially, socially, emotionally and professionally as a result."
In the second incident on late March 24, 2007, Tarala entered the cell where Smith was sitting on the floor.
According to the investigation, Smith was compliant but a profanity-spewing Tarala grabbed her by the hair, struck her back, neck and shoulders, banged her head on the floor, and then lifted her by the hair onto her bed. He also put his knee on her back to hold her down.
Both Tchorzewski and another guard later admitted their initial reports of the incident did not reflect what had occurred because they felt intimidated by Tarala.
He refused to talk to the investigators on advice of his lawyer.
Jurors spent Tuesday afternoon reading the 30-page document and Hamilton will be examined about it when the hearing resumes Wednesday.
In testimony Tuesday, Hamilton told the inquest she did the investigation at the request of Peter Guenther, executive director at RPC, a psychiatric prison run by Correctional Service Canada.
Smith, who frequently tied ligatures around her neck and was prone to acting out, had arrived at RPC in December 2006 from a prison in Nova Scotia, where staff had been unable to cope with her.
Hamilton, now retired, said the three-woman investigative team watched "disturbing" video of various incidents involving Smith.
"We were taken aback by it," she told jurors. "It was pretty difficult to watch."
However, the video was not directly useful to probe of the assault incidents but allowed the team to identify other issues, she said.
As part of the probe, they interviewed Smith, 19, for 45 minutes.
"Ashley was very open," Hamilton said, adding that the inmate was "young acting."
"Her voice was very timid but was very forthright with us."
As a result of the incidents, Smith was transferred out of RPC barely four months after her arrival.
Tarala would later be fired but was acquitted of criminal assault after the judge deemed Tchorzewski's testimony to be not credible and the victim was already dead and unable to testify.
Smith, of Moncton, N.B., choked herself to death in her cell in Kitchener, Ont., in October 2007.