I had been living in my rented home for about 5 months when neighbors told me that there had been a murder there two or three years earlier. Apparently, a past tenant was dealing drugs out of the home and was murdered (in the home) due to this. This information was not disclosed to me before moving in and I feel uncomfortable living somewhere known for drug activity. Do I have a leg to stand on as far as terminating the lease? Thank you!

Nope. How does something that happened 2-3 years ago affect you?

The landlord is under no obligation to disclose the previous renter's information. He could probably be sued by the former tenant's family if he did.