Can one investor sue another?

[Liliana Villanua]

my investor and the investor from an agent at my R.E. Office are using the same contractor. The other agent's investor is treatening to sue my investor because he is stating that the contractor used his money on my investors property. My investor has paid the contractor in full for the construction. 

He is treatening to put a mechanics lien on the property. I don't believe he has any solid base to do that . Does he has any recourse?