"CAI ST ALB VT" is Century Arms International of St. Albans Vermont.
Your import mark is an older version. The new CAI import mark is "CAI GEORGIA VT" which stands for Century Arms International of Georgia, Vermont.
CAI's import mark is often critized since last year when they switched from putting the marking on the barrel to the receiver. The newer CAI import mark is known as the "billboard" of import marks and is usually despised for its size.
Alas, something I know something about.
You said someone gave you this Luger. Do they have anymore and do they need another friend, relative or adopted son?