Missouri Investigators said Monday they were looking at the possibility that seven people found dead in an apartment were killed by carbon monoxide.
The victims were discovered Sunday after a 911 caller reported a "strange odor."
Kirksville Police Chief Jim Hughes said a fire department carbon monoxide detector gave a high reading, but they had not located the source of the poisonous gas.
The home heating system was functioning properly, but a van parked in the garage was taken to a crime lab for analysis, he said.
Lisa Lewis said her daughter, Maranda McDermott, 23, and McDermott's children, Adam McDermott Jr. and Melina McDermott, were among the dead. Adam turned 1 on Thursday, and Melina would have turned 2 on Dec. 30.
Relatives identified two of the other victims as Jeremy Liner, 19, and Reginald Washington, 21. The other victims were a 21-year-old man and 21-year-old woman.