Teagan, 8, was found dead in the trunk of her mother's car in Surrey, B.C. on Wednesday.
Her father, Gabe Batstone — Lisa's ex-husband — told CBC News at his home in Ottawa that he spent time on Sunday and Monday with his daughter in Vancouver, time he described as "incredibly important, but incredibly pedestrian".
"We ordered room service … We ate macaroni and cheese and held hands and went to the pool. Who thinks the last time they’ll see their eight-year-old is getting inserts preparing for braces?
"You can't prepare for that," he said. "There's no training."
Batstone said the toughest moment so far was telling his other children about Teagan's death.
"You sob, you cry. You tell a three-year-old and an eight-year-old brother they will never see their sister …"
The Batstones separated six years ago, then divorced. Custody of Teagan went to her mother but, Batsone said, there were "incidents" he believes should have brought that decision into question.
A suicide attempt by her mother meant Teagan went to live with her father for a while — an arrangement he says he tried to extend.
He called the resulting decision a "heartbreaking, crushing moment."
"A month after [the suicide attempt] we were forced to return her. Lisa was the primary caregiver as decided in court, and apparently attempting to abandon your child through suicide did not meet the threshold."
While she may have tried to hurt herself in the past, the CBC has no information to suggest she ever wanted to hurt her daughter.
An active member of White Rock Baptist Church for six years, Lisa Batstone "loved her daughter to bits,", her pastor, Ellis Andre, told CBC News. "[This] was totally out of character, the last thing we expected."
However, he said, Batstone's behaviour — which was punctuated by swings from elation to depression— had become more erratic, intense and "out of control" over the past three months.
"There was an increasing desperation taking place, she was seeing a counsellor," Andre said. "I encouraged her to see a psychiatrist because I thought medication may be helpful to her."Alarm raised
He said Batstone had been in contact with him over the weekend from a zip-lining camp she was attending with Teagan and "seemed to be happy."
But, just days later, she sent an "alarming" email that prompted the church to contact police.
"We acted immediately, not knowing that Teagan was already dead at the time," Andre said.
Gabe Batstone said he and his ex-wife weren't in a custody challenge, that their recent communications about Teagan were normal and mundane, and that there were no signs of "active, intense danger."
In her first court appearance on Thursday, Lisa Batstone asked to see a psychiatrist and a doctor. Her next appearance is scheduled for Dec. 18.
Teagan's father said he's hoping for a deep investigation and substantive change in family law.
"It's not about [me being] better, or judgment," Gabe Batstone said. "There were two home environments that were available to Teagan, and we collectively didn't, unfortunately, choose the safest one. And terribly, it played out in a way that ended her life so many years too soon."
"Something's broken. Something needs to change. …That can't happen to someone else. It just can't.
"It's the worst thing you could ever imagine."
With files from Ashley Burke and Jesse Johnston
ALSO ON HUFFPOST: