I need information about colorado dept of human services problem with falsely accused child abuse?

I live in Fort collins Colorado and recently my close freind was accused of child abuse and using meth. I have known this person for 3yrs and we are very close. They took her daughter out of school for questioning about her father and her mothers ex boyfriend. She was also subjected to a drug test which came back neg. Her daughter had a test for sexual abuse and was also negative. She tells me she has no idea who accused her but suspects her mother seeking revenge. My question is, is it true they wouldn’t have to tell her who accused her and if so can she find out who made this false complaint. I thought maybe since she totally satisfied the dept. of human services investigation she would have a right to know who did this to her. It has caused a wonderful person lots of stress. This all happened in Larimer County in colorado. I know they DHS was doing their job but the person who did this was totally seeking revenge to accuse a great mother and great little girl. Thanks