Was there life on Mars? (the planet not the snack)

'' Decades after analysis of data from soil samples obtained by NASA's Viking probes concluded there was no life on Mars, new analysis has led to conclusion that the first analysis was flawed and that the probes actually found evidence of life on Mars.
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The two 1976 NASA space probes, Viking 1 and Viking 2, had brought back photographs and conducted three experiments on Mar's air and soil samples. The experiments looked for evidence of life on Mars. Only one of the experiments called the Label Release experiment found evidence suggestive of life. The Label Release tests found signs of CO2, a gas produced by all living organisms in the soil. But scientists ignored the evidence from this experiment and concluded that though there were signs of geological activity, there were no signs of biological activity on Mars.
The latest analysis by Miller et al., took a different approach based on the idea that biological processes, being more complex than known non-biological process, are associated with greater complexity. ... '' [source]