They have known one another only six years, but Kathy Peterson insists her sister Patti Becht's devotion to her family was never in doubt.

It was Becht who helped her mother track down Peterson, who had been put up for adoption decades ago. It was Becht who doted on her three children, even through bouts of depression and the trials of divorce, remarriage to the same man and divorce again.

So Peterson, like so many others who know Patricia Ann Becht and her children, said Wednesday that she is struggling to understand how Becht could potentially have killed her son Michael, a sweet, autistic 10-year-old known in the neighborhood as Mikey. Or how she potentially could have harmed her daughter Erica, a bespectacled 11-year-old who looked up to her 16-year-old sister Cara.

"I didn't really know what was going on with her, but there had been some deep underlying issues that weren't dealt with that had to have caused this," said Peterson, of Grand Marais, Minn. "Something like this would not have happened if she was in her right mind."

As family members arranged Wednesday to bury Michael Vonheath Becht Jr., South St. Paul Police remained mum on why they consider Becht, 42, the sole suspect in the death of her son and the unspecified injuries inflicted on her daughter and herself.

A relative found the boy dead in the duplex at 716 1st Av. about 5:30 p.m. Monday. Becht and her daughter were found in medical distress in the home.

Patricia Becht, who was conscious and breathing, was taken to United Hospital in St. Paul. The girl, who was unconscious and breathing, was taken to Children's Hospital in St. Paul, where she is in stable condition. Both are expected to survive.

Police say that no weapons were used on the children, and there was no evidence of violence. Officials said it may be today at the earliest before an official cause of the boy's death is released. His mother remained under guard Wednesday.

In January 2007, Becht obtained a harassment restraining order against the man she married twice, Michael Becht Sr., saying in an affidavit that he was "a threat to me and my children." They last divorced in 2005. She said that he had called Michael Jr.'s school pretending to be a doctor. The order was dropped two months later for "insufficient proof to support restraining order," according to court documents. Michael Becht Sr. could not be reached.

Peterson said she came to know Patti Becht as someone who had her difficulties but loved her family unconditionally.

"Did she want to take them away from suffering?" Peterson said. "She had to have been dealing with something. I don't know how to explain it."

Abby Simons • 612-673-4921