I found lots of droppings in my apartment. (came back after 3 months) Could anyone identify this?

I saw a rat in my kitchen around a month ago. -I setup glue traps and one got him, but he got out of it and I found the trap 20 feet away from its original location. -I setup snap rat traps baited with various things I read worked (cereal, granola bar, peanut butter, cheese) in the areas I've seen/heard it. No luck. -I used steel wool and expanding foam to close any holes I could find anywhere. -I "locked" up all food items. It had gotten into rice, pasta, etc. in the pantry. I believe any food is now inaccessible to the rat. We clean up after dinner and don't leave food out. I am somewhat at wits end. It has been under the kitchen island making tons of noise for several nights now. There was a hole under the sink where the plumbing came up from the garage. I shoved steel wool in there and went crazy with foam. I think the rat has been working on trying to break that hole open. I really don't want to poison it and have it die in a wall or something. Any other suggestions? It is so frustrating knowing where it is and sitting and hearing it for hours and not being able to do anything about it. I think it might have come in when bringing in groceries or something and not through a hole.