My friend is under investigation and he has destroyed incriminating evidence, how much trouble is he in?

So my friend is under investigation by the feds and local law enforcement after he said some stupid violent stuff online. He told me that he lied to them and that he has destroyed evidence that it is him by ripping out his old hard drive and throwing it in the river along with his backup drive. Then he got a new phone (they have his IMEI number) and got a new wifi network system complete with a new router and etc. He says that his parents is helping cover for him. How much trouble is he in?

My friend is under investigation and he has destroyed incriminating evidence, how much trouble is he in?
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