The Professor of Immortality by Eileen Pollack

Maxine is adrift. She once had a husband, a successful career and a clever son working in Silicon Valley. Now, she isn't as quick to get to her job as a noted professor at the University of Michigan, her husband is dead and her son has gone off the grid plus there is a madman called the Technobomber who is blowing up people and it may be someone she and her son know quite well. She worries that there may be a connection to the bomber and her son's disappearance and she also knows that in telling what she knows to the FBI she may be giving up her son. This is a classic tale of doing the right thing, taking a hard look at our own mortality and finding our own place in the universe.