Chlorophyll was reported by spectral analysis of the Martian surface and on newly-appearing material on the lander deck [Levin does not say, but he likely means the Pathfinder lander]. Although the respected scientist who made this claim withdrew the published peer-reviewed publication, inducement is suspected.
Some further digging reveals this interview, in which Levin claims
He [Levin] told me [interviewer] of Carol Stoker, who, in 2002 thought she had detected traces of chlorophyll on Mars, strongly suggesting current life. [...] Levin believes that "NASA made her withdraw the paper."
Around the same time, in 2002, The Guardian reported on the discovery of chlorophyll also:
The Nasa team analysed data obtained by the Pathfinder mission to the red planet which suggests there could be chlorophyll
So. If we believe Levin, there is a peer-reviewed, published, and then retracted paper reporting on the discovery of chlorophyll on Mars. It was likely published some time around 2002, and the author list likely included Carol Stoker. I would very much like to find this paper.