First, you should report this to the authorities. That should be your number one consideration. Second, after you have helped them with their investigation, you should consider consulting with a personal injury attorney in your area.
The Texas Civil Practice and Remedies Code Chapter §16.003(b) provides: A person must bring suit not later than two years after the day the cause of action accrues in an action for injury resulting in death. The cause of action accrues on the death of the injured person. It is important you contact a lawyer within 2 years to make sure to protect your claim. However, due to the chances that evidence could be destroyed or altered, you should contact an attorney immediately.