The east-side neighborhood had reeked off and on for several years, and residents had blamed the odor on a broken sewer or a nearby sausage shop. Now most think the smell came from decomposing bodies.
Neighbors blamed Wednesday's renewed odor on increased activity near Sowell's house.
The FBI, which has offered technical help in the investigation, said the timing of a thermal-energy search of the property would be up to city police, who didn't indicate when that would start.
Makers of thermal-imaging devices say they can help police find buried bodies because dirt that has been turned over radiates heat differently than compacted soil.
Police discovered the first two bodies and a freshly dug grave Oct. 29 at Sowell's house after officers came to investigate a woman's report that she had been raped there. Sowell had fled the home and was arrested two days later.
In all, the remains of 11 women have been found in Sowell's home or yard. All of the women were black and most had been strangled, the coroner said. Nine have been identified through DNA and dental records.
Police said Sowell lured women — often those who were homeless or living alone and who abused drugs or alcohol — with liquor and attacked them in his home.
Sowell has asked for a court-appointed attorney, but court records don't reflect that one has been chosen for him.
Scott Wilson, an FBI spokesman in Cleveland, has said investigators are reviewing its national database of unsolved crimes for any clues to possible connections to Sowell, particularly at locations where he served in the military.
Sowell was in the Marines from 1978 to 1985 and spent time in California, the Carolinas and Japan. Fox News reporting.