"I will never be able to forgive myself for being so many hours away when you needed me the most," Desiree Young wrote in a letter she released to NBC's "Today" show. "I pray that you come back to me because I am afraid that I can't live without you.
"I miss you every second of every day," the letter continued. "I would give my life for yours, I just want you back safe. You must come back to us."
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Kyron, of Portland, Ore., has been missing since June 4, when he got dropped off at Skyline School in northwest Multnomah County by his stepmother, Terri Horman.
Horman, 40, has taken a polygraph test and was going to take a second on Saturday, her friend, Jaymie Finster, told The Oregonian newspaper. Horman has been a prominent figure in the investigation because she was the last to see Kyron, but police are not calling her a suspect, The Associated Press reported. Authorities would not comment on whether lie detector tests had been given to anyone.
Young, 38, sounded a hopeful note that she will be reunited with her son, seen in a photo with her wearing a broad smile.
"When you come home I will show you all of the things that everyone did for you, just to find you," she wrote. "There are so many wonderful people working on this case and they are going to find you soon."
The letter continued: "I would give anything to run my fingers through your short hair again. I miss having you to hug anytime I want. Nighttime is always hard for me. I miss you so much and want you back here so that I can protect you from all of the horrible things in this world."
It ended, "I love you very much! Momma."
Authorities have asked the community to fill out questionnaires seeking more information about Kyron's disappearance. At least 100 parents returned the form to officials on Sunday, according to The Oregonian.
It's too soon to say if the information will be helpful, Sgt. Travis Gullberg of the sheriff's office told the paper. "It's going to take some time to go through it all," Gullberg said.
Among the parents was Chris Feryn, whose son answered the questions, according to the paper.
"He didn't have a lot of information the first time," Feryn said of his son, who just finished seventh grade. "We'll try to help out however we can."