Three NASA scientists,Dr. David McKay, Dr. Richard Hoover, Dr. J.E.
Brandenburg, respectively published peer-reviewed articles that
confirmed there was life on Mars.

Dr. David McKay has published many articles on meteorite ALH84001.He
and his research team has never stepped back from their initial
conclusion that there was past life on Mars:
http://en.wikipedia.org/wiki/Allan_Hills_84001#Possible_biogenic_features

Dr. Richard Hoover found alien microbes in meteorites Ivuna and
Orgueil: http://www.foxnews.com/scitech/2011/03/05/exclusive-nasa-scientists-claims-evidence-alien-life-meteorite/

Meteorites Ivuna and Orgueil belong to the CI group of meteorites. Two
days ago, Dr. J.E. Brandenburg found the CI group of meteorites
originated from Mars: http://journalofcosmology.com/BrandenburgMeteor.pdf

So, the alien microbes found by Dr. Hoover actually originated from
Mars. Past Martian microbial life has been verified by these three
NASA scientists.