Amino acid molecules produced in the lab are 50% left handed and 50% right handed. However, amino acids in fossils can be uneven-handed (over 50% left-handed, for example). This unevenness or excess of left-handed amino acids is a sure sign of past life (note 1). This sign of past life is found in organic molecules in meteorites (notes 2, 3). So, organic molecules in meteorites are post-biotic fossils.
Note 1: “Homochirality probably constitutes the most reliable indicator of the biological vs. abiotic origin of organic molecules.” [link to www.esa.int
Note 2:"Fragments of the Tagish Lake meteorite contain amino acids that are predominantly left-handed, as in life." [link to www.panspermia.org
Note 3: “In the new research, the team reports finding excess left-handed isovaline (L-isovaline) in a much wider variety of carbon-rich meteorites.” [link to www.nasa.gov
Added on Sept. 3, 2011:
Explanation on fossils’ amino acids
When organisms die and form fossils, the percentage of their left-handed amino acids decrease gradually from 100%, then fluctuates around 50 % until the percentage finally becomes stable at 50%. Abiotic amino acids always are 50% left handed. So, small variations from 50% of left-handed standard (protein) amino acids indicate past life of the sample material.
Even-handed amino acids do not prove past life as they are found both in non-life, and in not-well-preserved fossils, and very ancient fossils. Uneven-handed standard amino acids prove origin in life as they are found only in well-preserved fossils.
Ref.: [link to en.wikipedia.org