Basically, discovering DNA is sufficient but not necessary to discovering life.
And if we did find DNA (itself a monumental discovery), sequencing it would be the next most important bit of information we could want, since it might allow us to check if there is some relation to life on earth.
And if we did find DNA (itself a monumental discovery), sequencing it would be the next most important bit of information we could want, since it might allow us to check if there is some relation to life on earth.