We use the combination of laser ablation ionisation mass spectrometry (LIMS) and optical microscopy for the search of signatures of life. This a powerful combination of experimental techniques to identify microbial life on or near the surface of planetary bodies. Microbial life we want to investigate in situ is either extinct life in form of fossils in minerals, or extant life extracted from some habitat. First, potential life forms are identified by optical microscopy from these collected samples. Subsequently, identified locations on the samples are investigated by laser ablation ionisation mass spectrometry to obtain the element and isotope signature of the putative life form and of the surrounding host material. Since microscopic life forms are searched for the LIMS experiment is operated also with lateral and depth resolution of µm and nm, respectively. From the presence of specific bio-relevant elements in the sample necessary for life, starting with carbon, and elements participating in the metabolic processes, single microbes have been detected with high efficiency. In addition, isotope abundances are measured, for example we present δ34S/32S measurements with respect to metabolic process, or δ 60Ni/58Ni measurements, which is part of enzymes. By switching the laser to laser desorption mode also complex molecules can be studied with our LIMS instrument. In summary, from the elemental composition, from specific isotope ratios, from the presence of telling chemical compounds, and from the mineralogy of the host material (in case of fossils) together with the morphology of the investigated feature we can distinguish between a microbial and abiotic matter. At present we have a prototype version of the LIMS instrument suite operating, that is capable of accurate and sensitive element, isotope, and chemical studies with high lateral and depth resolution and is able to perform an investigation of natural samples.