Thank you to the 22nd district police department and Michelle P for scanning Scooby's microchip, and sending it to Microchip Help.
The microchip for Scooby was never registered, but the Nebraska Humane Society had his adoption information from 2007.
The number was outdated, and when looking the name up, Chicago addresses came up. Her name, however, showed that she had passed away in 2017.
I contacted the first name that came up to all the same addresses both in Nebraska and Chicago, to see if they knew who he currently belonged to, and was told, "that was my wife, and Scooby went missing from me a little over a year ago. I looked for him for a long time." She asked where he was, and not even an hour later, he was picked up. She is very happy he is home, but said he has really aged in the last year. He is deaf and possibly completely blind.
Welcome home Scooby. You have been missed.
*extra special thanks to Sissy from the 22nd for cutting his nails*