"I have no definitive proof that you are Kira, but I have been and will continue to be sure that you are. You are now under my supervision 24/7. And before you begin to resent it, I'll tell you: it's not my whim."

After these words, L secures one handcuff to your left wrist. As you run a glance along the long chain, you realize that the second handcuff is secured to L's hand. You are now chained indefinitely until the detective is convinced of your innocence.