If an ocean is confirmed then we will want to pentrate the ice layer to search for life within the ocean. The most ambitious of the space missions now planned to search for planets of other stars aim to do more than just find such planets - they should be able to determine whether the planets have developed life. These systems consist of an array of space telescopes arranged such that they can use the destructive interference of light to suppress the light of the star, and reveal the much fainter planet. When these missions find an earth-like planet they can then measure its spectrum which will reveal the mix of gases in its atmosphere. The detection of ozone in the spectrum would indicate that the planet has oxygen in its atmosphere.
Oxygen indicates that living organisms undergoing photosynthesis are present.
On Earth it is believed that oxygen only began to build up in the atmosphere about 2 billion years ago due to action of photosynthetic cyanobacteria. SETI can potentially detect life at much greater distances than other techniques if their transmitters are powerful enough. However, unlike the other techniques which can detect microbial life, SETI can only detect intelligent life, and then only if they are sending signals in our direction. This raises the question of whether life inevitably evolves towards complex organisms and to the eventual development of intelligence. If so, SETI could be a very powerful technique.