There are two aspects of the matter.One is criminal ie causing death due to negligence and second is compensation to employee under Employees compensation Act. Because of limited number of staff I take it that your employees were neither covered under ESI Act nor you had got them insured with any other insurer. Employees compensation is paid when the death occurs during the course of and out of employment. If death occurs due to negligence of employee or disobeying lawful instructions of employer in regard to safety, or for that matter when he was not on duty, the employer can not be held responsible. Therefore as far as compensation is concerned the liability might fall upon you. As far as criminal action is concerned, you have not detailed how the death occurred but so far you have not been named in FIR, but if the circumstances exists you can be added as an accused at subsequent stage either by investigating agency or by court. For the time being you relax on this front.
The duration of employment is not relevant in both cases but age and salary of the employee is relevant for calculations of compensation.