It has been a challenge to conclusively determine what organic life exists on Mars. Airspacemag.com has a great piece on perhaps tweaking the methodology used to search for life.
Curiosity’s view of rock strata at the foot of Mt. Sharp on Mars. Finding signs of Martian life will require scientists to keep an open mind. The near absence of organic compounds on Mars has long been a conundrum to those searching for possible life on the Red Planet. […]