CLEVELAND — FBI agents sifted through dirt with rakes and shovels Saturday in the backyard of a suspected serial killer's home and ran a thermal-imaging device across the ground near the area where the decomposing bodies of several women were found.

The agents worked for about four hours at the home of Anthony Sowell, crawling beneath the front porch and removing bricks and other debris. One agent had a tape measure, while another snapped pictures and a third marked locations with orange paint. They finished up around 1:30 p.m.

On Friday, the FBI worked at the red-painted house next door to Sowell's to do thermal imaging, X-rays and other tests. 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, the coroner said. Ten have been identified through DNA and dental records.

The 50-year-old Sowell has been accused of luring women to his home with the promise of alcohol or getting high. Authorities say he then strangled them and left their bodies in his house or buried in the backyard.

Sowell remains in jail on $6 million bond on five preliminary charges of aggravated murder. Sowell's lawyer, Brian McGraw, said he met with his client Friday at the county jail, but he declined to comment on the case or describe his conversation with Sowell.

Cleveland Police Chief Michael McGrath visited the scene Saturday and watched agents work in the backyard. He declined to comment.

Sowell's three-story house is cordoned off by yellow police tape and guarded by police around the clock. But onlookers appear drawn to it: 20 to 25 people stopped by Saturday morning to watch the agents work.