Scientists Unsure if Methane at Mars Points to Biology or Geology

Three research teams have combined forces to find traces of methane on Mars, and at last they have found it. This finding has enabled several new theories to be unfolded for consideration as to how the methane got there. The two most likely theories as to how methane became present on Mars are: volcanic activity or meteorites landing on Mars containing methane. However, several theorists are pushing for the theory that the methane was produced by microbial life. The methane detected were said to have been detected by ground based telescopes by NASA scientist Michael Mumma and Catholic University of America researcher Vladimir Krasnopolosky. They believe that because methane has a short half life in Mars atmosphere, about 300 years, the methane had to be some how replenished. The likely answer to this speculation is methane seeping through the crust caused by prior volcanic activity.
http://www.space.com/scienceastronomy/mars_methane_040329.html