Kansas City, Mo. ? A defense attorney for convicted killer Wesley Purkey said his client thought the young girl he picked up at a small Kansas City grocery store in 1998 was a prostitute who got into his vehicle voluntarily.

Purkey, 51, of Lansing, Kan., is being tried for kidnapping, raping and fatally stabbing 16-year-old Jennifer Long of Independence, Mo. U.S. Atty. Todd Graves has said he would seek the death penalty if Purkey is convicted.

With Long’s family looking on, prosecutors displayed chilling evidence that they say proves Purkey’s guilt: a muddied, 5-by-2 toolbox that was used to store the girl’s body; the electric chain saw used to dismember her; and photographs of the fireplace where her remains were burned.

The defendant “painstakingly and methodically covered his tracks,” in getting rid of much of the physical evidence, Graves told the jury Thursday.

But defense attorney Fred Duchardt denied that there had been a kidnapping. He said Long went willingly with Purkey to smoke crack cocaine and drink gin and orange juice.

Purkey, who is serving a life sentence in Kansas for killing an elderly Kansas City, Kan., woman, confessed to killing Long because he wanted to get out of Kansas, Duchardt said.

The attorney said Purkey had made some enemies in Kansas prisons and thought it would be easier to do time in a federal facility. Duchardt said the FBI never told Purkey he might face the death penalty, and instead led him to think that he would serve a life term in a federal prison if he admitted that he kidnapped and killed Long.

Kidnapping is a federal crime if the victim is taken across state lines.

On Thursday, both sides tried to recap the final hours of Long’s life.

At the time of her disappearance, Long was attending East High School, a now-defunct Kansas City, Mo., magnet school.