A once high ranking scientist, but after coming into contact with the Red Marker, Nolan Stross began developing the same dementia that all others who come in contact with it, including Isaac Clarke. Driven mad, he murdered his wife and baby boy, believing them to be Necromorphs. Since then, he was placed in stasis on the Sprawl for research purposes.
Dead Space 2
Much like Isaac, following the Necromorph outbreak on the Sprawl, Nolan was able to escape from the psychiatric ward of the medical department and become free once more. Nolan occasionally contacts Isaac, saying that together they can destroy this new marker and stop the outbreak. At the same time, Nolan's dementia and mental state quickly deteriorate. He is pushed to follow the images of his dead wife and child and is often reciting the steps to destroy the marker, "Step 1: Step into the darkness, Step 2: The screws go tight, all around, Step 3: Stick a needle in your eye."
Following an encounter with Ellie Langford, Nolan officially joins up with Isaac as his condition continues to eat away at him. Nolan at one point ends up biting Ellie and eventually, overcome by his dementia, stabs her eye out, seemingly in an attempt to act out "step 3," ending up alone in the mines of Titan. Later, he ambushes Issac and tries to show him, too, what he can see. Isaac quickly disarms him and stabs him through the head, killing Nolan.