New footage shows Nick Reiner walking around in Santa Monica hours before his parents’ dead bodies were discovered in their Brentwood home … and he’s heading toward the hotel he checked into.

TMZ obtained surveillance video from a local business on Santa Monica Pier. You see Nick walking down the sidewalk, towards the Pierside Santa Monica hotel.

The video was shot around 4 AM Sunday … and Nick looks like he’s carrying a black backpack and wearing a hat … just like the video we obtained of him at a Brentwood gas station earlier in the evening.

We don’t know if this video of Nick was shot before or after he allegedly murdered his parents.

What we do know is that he checked into the hotel approximately 6 minutes after he’s seen in this footage. Sources with direct knowledge told us no one saw any blood on Nick when he arrived at the hotel at 4:15 AM.

We broke the story … hotel staff found blood in the shower and on the bed in Nick’s room … and the window was covered by bed sheets.

Nick was arrested Sunday night near USC campus in downtown Los Angeles … and he’s since been charged with murdering his parents, Rob and Michele Reiner.

In footage from his arrest, Nick has a red backpack … so it looks like he switched bags at some point after going to the hotel.