Food usually will do the trick. He may be wary of humans so be patient and take time, maybe put the food out and not try to catch him until you are sure he won't feel the need to do the fight or flight thing unless he seems to be in danger.

Although raw meat may work, cooked meat will not spoil as quickly and is usually easier to digest. Canned tuna or salmon are nice and smelly and attract most cats (though some hate fish and too much tuna can be a problem).

If you can, putting out some dry cat food and a bowl of clean water would be a kindness. In many areas clean water is hard to find and cat food (even budget kinds) is made to provide cats with all they need. Dry food won't spoil or get infested with insects as quickly as soft food.

Bless you for taking time!

What are your plans for the skinny one?