Authorities in Colorado say the bodies of two young girls believed to have disappeared with their mother this week were discovered in “mostly full” gas and oil tanks owned by their father’s previous employer. Sources close to the investigation told the New York Post the killer likely placed their bodies in the Anadarko Petroleum tanks to hide the smell of decomposition. Police said late Thursday that they have “strong reason to believe” the remains belong to 4-year-old Bella Watts and 3-year-old Celeste Watts. The girls were at the center of a high-profile missing-persons case after they disappeared Monday along with their mother, 34-year-old Shanann Watts, who was pregnant. The case turned into a homicide investigation late Wednesday with the arrest of Christopher Watts, the girls’ father and Shanann Watts’ husband. Watts had pleaded for the family’s safe return in a TV interview after their disappearance, but is now accused of killing them, and he allegedly confessed to the crime while in custody. Investigators did not give a precise location on where the bodies were found, but said the two young girls were found near their mother.