Albert Barnes Commentary Daniel 6:12

"Then they came near, and spake before the king concerning the king`s interdict: Hast thou not signed an interdict, that every man that shall make petition unto any god or man within thirty days, save unto thee, O king, shall be cast into the den of lions? The king answered and said, The thing is true, according to the law of the Medes and Persians, which altereth not." — Daniel 6:12 (ASV)

Then they came near - That is, they came near to the king. They had detected Daniel, as they expected and desired to do, in a clear violation of the law, and they lost no time in informing the king of it, and in reminding him of the law which he had established. Informers are not likely to lose time.

The king answered and said, The thing is true ... - It is undeniable, whatever the consequences may be. There is no reason to suppose that he still had any suspicion of their design in asking this question. It is not improbable that he suspected there had been some violation of the law, but it does not appear that his suspicions rested on Daniel.