[mothered]

If they do open an investigation I'll claim I found the package hidden somewhere and go through with a legitimate refund on the item.

Ultimately It's your call, but do note that an Investigation does have a high success rate.

It's simply used to comply with company protocol to move forward with the claim.

I just received the item, and looked at Amazon to see that a picture was taken and posted of where the item was placed at my house.

Is the DNA method still effective at this point?

Perfect for the DNA. When a signature Is not present on the carrier's manifest, It's very difficult for the company to establish whether It was accepted by the account holder.

Given you didn't sign for It, you didn't personally receive It.