Dykes was killed Monday by SWAT team members during a gunfight when officers raided the bunker and rescued the kindergartner unharmed, officials said. With the work of bomb experts concluded, Dykes' body could be safely removed from the bunker, the FBI said.
An autopsy was planned Thursday and the FBI said evidence-collection and review teams had already begun the next phase — sifting the crime scene.
The FBI said after the raid that the 65-year-old man had planted one explosive artifact in a ventilation pipe used by negotiators to communicate with him in his underground bunker in the bucolic farming community of Midland City. The agency said a second device was found in the roughly 6-by-8-foot hand-dug bunker. Both were safely removed.
FBI Special Agent Paul Bresson said in an email late Wednesday that the technicians who scoured the 100-acre property in the days after the end of the standoff had "completed their work and cleared the crime scene."
"No additional devices were found," he added.
Dale County Coroner Woodrow Hilboldt told The Associated Press late Wednesday that he was waiting to pronounce Dykes dead. He added that the autopsy would be held at the state forensic laboratory in Montgomery.
Bresson, meanwhile, said evidence review teams now processing the crime scene could take two or three days to finish their work. A shooting review team from Washington also is reviewing the hostage-taking episode that began Jan. 29 with the attack on the school bus.
Authorities said Dykes boarded the bus full of children and gunned down drive Charles Albert Poland Jr. as he sought to protect the 21 children on board. According to officials, the gunman then seized a 5-year-old boy and fled with his hostage to the nearby bunker, setting up the standoff that had captured national attention.
The boy's rescue was carried out by the FBI's hostage response team, which serves as the agency's full-time counterterrorism unit, FBI agent Jason Pack said Wednesday. Trained in military tactics and outfitted with combat-style gear and weapons, the group was formed 30 years ago in preparation for the 1984 Olympics in Los Angeles.
Composed of FBI agents, some of whom have prior military experience, the team is deployed quickly to trouble spots and provides assistance to local FBI offices during hostage situations. It has participated in hostage situations more than 800 times in the United States and elsewhere since 1983, the FBI said.
"As an elite counterterrorism tactical team for law enforcement, the HRT is one of the best, if not the best, in the United States," Sean Joyce, deputy FBI director, said in a statement.
The FBI also brought out an array of military-style equipment including armored personnel carriers and combat rifles. Drones also flew large, lazy circles overhead.
According to a U.S. official, about a dozen Navy Seabees in special naval construction unit helped authorities build a mock-up of the bunker to plan the FBI assault. The official, who was not authorized to discuss the rescue effort, spoke on condition of anonymity.
"This was a classic, textbook situation," said Clint Van Zandt, a former FBI negotiator who worked with the hostage rescue team repeatedly before retiring in 1995.
Building a replica of Dykes' bunker, practicing an assault, negotiating Dykes into a sense of security and even sneaking a camera into the shelter are all part of the agency's tools, said Van Zandt.
"This is what negotiators and team members train to do all the time," added Van Zandt, president of Van Zandt Associates, Inc., a Virginia-based company that profiles and assesses threats for corporate clients. "To me, there was nothing unique in this other than it played out in front of the world."
FBI and other officials said the team exchanged gunfire with Dykes and killed him before rescuing the boy, whom law enforcement officials only identified by his first name, Ethan.
Hostage-rescue methods were far from the minds of folks in Midland City
On Wednesday, Ethan's sixth birthday, Midland City residents sought to resume a normal life after the ordeal that upended lives in the tight-knit rural community nestled amid peanut and cotton farms.
The boy, who has Asperger's syndrome and attention deficit hyperactivity disorder, was said to be acting like a normal kid despite his ordeal.
Officials hope to eventually throw a party to celebrate Ethan's birthday. They also plan to honor the memory of the slain driver.