Is your wife really responsible for the alleged dowry death case or she has been falsely implicated being the relative of accused no. 1?
If she is really cruel and has really torchured the deceased lady and has a hand in causing her death then go ahead and see IF any legal ground is available to you for divorce after consulting a good advocate and briefing him with full facts.
But if your wife is falsely implicated as accused no. 4 then, this is the time when she needs ur support the most. Ask her why she wants money? and see if her demands are justified and then give as per the need. If she needs it for hiring the services of a lawyer for defending herself then, you should provide as per your capacity. Is it proper to leave your wife during the most troublesome period of her life when you are supposed to stand behind her firmly?
BTW, wife facing a criminal trial and demanding money is no ground for divorce.