"I'm just very, very confident (that) law enforcement officers ... checked every single lead, and if there was one bit of evidence (they would have) followed it up very, very aggressively," he said.
"In hindsight, we may find out that maybe we did, but that's going to be in hindsight."
Relief, joy as victims reunite with family
For the first time in years, relatives of Berry, DeJesus and Knight -- whom Perez described Wednesday as "safe and healthy" -- don't have only memories to fall back on. They can look forward, and move on with their lives.
Barbara Knight told "Today" that, as of Wednesday, she still hadn't talked with her daughter Michelle. Michelle Knight, now 32, was then in a Cleveland hospital in a good condition.
"She's probably angry at the world, because she thought she would never be found," Barbara Knight said. "But thank God that somebody did."
Asked what she would tell her daughter, her mother said, "I love you and I missed you all this time."
Well-wishers welcomed Berry and her daughter on Wednesday to a family home in Cleveland that was decorated with balloons and stuffed animals.
"We are so happy to have Amanda and her daughter home," said her sister, Beth Serrano.
A similar scene played out at a DeJesus family home, where relatives embraced their long-lost relative.
Sandra Ruiz said that her niece, DeJesus, is "ecstatic" to be back with her relatives. When the now 23-year-old arrived at the house, "she was happy, she looked at the house and she wanted a tour."
"What more can she say -- her face, her expression, her smile, (her) hugging says it all."