St. Paul, MN (KROC-AM News) - It appears we may never know the source of the toxin producing bacteria that claimed the life of a central Minnesota child last month.

According to a Caringbridge website that was set up by her parents, three-year-old Kallen Maresh died after developing an E. coli infection that resulted in kidney failure. Her five-year-old brother Kade also became severely ill from the infection, but is now recovering at the family’s home in Wright County.

The Minnesota Department of Health says state epidemiologists have completed their investigation into the infections, but were not able to identify a specific source of the killer bacteria. The investigation looked at all known potential sources of E. coli, which includes common food products like ground beef, leafy green vegetables and raw milk. The list of possible sources also included swimming, person-to-person transmission among family members or child care settings and contact with farm animals.

“Unfortunately, we were not able to identify the source of the children’s infections,” said MDH State Public Health Veterinarian Joni Scheftel. “In particular, we did not find a connection with a petting zoo that the children visited, despite extensive testing of the animals.”

Health Department officials say there been no additional cases of illness blamed on the same strains of E. coli, but they are continuing to monitor for new cases that could pinpoint the source of the bacteria.