But he said it was Mr. Franks who emerged as the chief suspect, drawing the attention of investigators one day after Opal Jo Jennings was abducted on March 26, 1999.
Special Agent Andrew Farrell was on the stand for nearly four hours Thursday in Mr. Franks' aggravated kidnapping trial as prosecutors sought to show jurors that Mr. Franks is the prime suspect. Prosecutors and defense attorneys rested their cases Thursday, but some rebuttal witnesses may be called Friday before closing arguments begin.
Mr. Franks, 31, of Fort Worth has pleaded not guilty to the charge. A jury in June deadlocked 7 to 5 in favor of conviction, forcing Tarrant County District Judge Robert Gill to declare a hung jury and leading prosecutors to seek a retrial.
On Thursday, Agent Farrell testified that Mr. Franks changed his appearance in the days after the abduction, drove a car similar to the one that witnesses reported seeing and gave an incriminating statement that he had picked up the girl.
Defense attorney Ed Jones launched a vigorous attack during a two-hour cross-examination of the FBI agent, getting him to concede that there were other suspects and other leads in the case.
Several witnesses, including some who were hypnotized, gave varying descriptions of the suspect and the suspect's car, the agent conceded.
Agent Farrell said investigators found no hair, blood or fingerprints in Mr. Franks' car linking him to the crime.
"There is no physical evidence," he said. Agent Farrell said the bureau received thousands of tips in the case including leads that Opal had been sighted.
"Most of the sightings were like 'I saw her at a gas station.' I checked leads on all the sightings," he said. "They are resolved as best they can be. Some of them are unsolvable."
Agent Farrell also said that on the weekend that Opal disappeared, a NASCAR race at the Texas Motor Speedway brought thousands of people into the North Fort Worth area around Saginaw.
"The race brought 200,000 to 300,000 additional people into the area," he said.
Agent Farrell said investigators interviewed the girl's family in the days after her disappearance and followed up on a statement attributed to her father that he planned to take her away. Investigators later were able to establish an alibi for Randy Crawford, the girl's birth father, placing him in Nashville, Tenn., at the time of the abduction.
Opal moved to Saginaw to live with her grandparents in September 1998. Prosecutors contend that Mr. Franks knew the North Hampshire Street neighborhood because his brother had once lived on the same street but had moved by the time Opal arrived from North Dakota, where she had lived with her mother.
Also Thursday, a friend of Mr. Franks, testified that he cut his hair, appeared "distant" and was without his familiar red baseball cap the day after Opal disappeared.
Vivian Largent, a friend of Mr. Franks and his wife, Judy, testified that he changed his appearance after the girl was reported missing. Witnesses told investigators that Opal's abductor had his hair in a long ponytail and wore a red baseball cap.
Ms. Largent said that she has known Mr. Franks for two years and was surprised to see him with shorter hair inasmuch as he said he wanted to grow his hair longer until he was in his early 30s.
Also Thursday, Mr. Franks' attorneys called Richard Leo, an associate professor of psychology and criminology at the University of California at Irvine, to discuss police interrogations. During a 12-hour police interrogation, Mr. Franks told police he took the girl to get something to eat, rejected her sexual advances and released her unharmed. But he immediately recanted.
Defense attorneys say Mr. Franks is mentally retarded. Mr. Leo said mentally retarded suspects who are interrogated usually are "more suggestible."
"They are not likely to understand the gravity of their situation," he said, "that they could go to prison or get executed."
When questioned by Tarrant County Assistant District Attorney Lisa Callaghan, Mr. Leo said he knew none of the specifics of the case.