“Psychotherapy in combination with medication. The tricky part is finding which medication works for each patient. One individual might take mood-stabilizers like lithium or Depakote, in combination with antidepressants such as Elavil or Prozac. It usually takes a while to find the right mix.”

“How does the condition change as the individual gets older, say, in the twenties?”

“Often it’s worse. At that age, they’re considered adults. Now they live on their own and set their own schedules. Some have substance abuse problems, which exacerbate their symptoms.”

“So, if they were to take OxyContin or Ecstasy—”

Bittner shook his head. “It could have terrible consequences. Increase the highs and lows. Push them over the edge.”

“So it might be difficult for someone with this condition to be in a relationship.”

“A big threat for people with Bipolar I is high-risk behaviors, which can mean multiple partners, excessive sexual activity, or relationships with abusive partners.”

“So apart from seeing a therapist and taking medications, how does someone with BSD deal with it?”

Bittner puffed his cheeks and let the air out. “Deal? It’s more like a battle. A daily, even hourly, battle. You can’t believe how hard this thing is. Sometimes it helps if they have something to focus all that manic energy on. Some consistent thing they can come back to, that can ride the ups and downs, and be an anchor for them.”

“A thing? Like a hobby or interest?”

“It’s obviously different for different individuals.”

“So it could be something like reading? Say, poetry?”

“Reading’s not so common because it requires concentration.”

“But for the sake of an example, let’s say it’s reading. And let’s say it’s the poetry of Keats.”

The two men looked at each other. “I told you, Lieutenant,” Bittner said. “I can’t talk about Elise.”

“And I told you I’m investigating a young woman’s murder.”

Bittner pulled himself upright. “All right, look. I’ll tell you something if it’ll help. But none of this is simple. It’s not like putting together a puzzle and finding a single answer. People with BSD like Elise often have trouble with boundaries, distinguishing between their thoughts and reality. Her father abandoned his family when Elise was three and rarely communicated with her. But he sent her a book of Keats poetry. Sometimes Elise believed her father was Keats and he was writing to her. What she thought or said about the poetry was not always connected to the real world.”

Mahler waited. He was beginning to think the doctor had been right from the start—that he really couldn’t say anything useful in identifying a suspect. He decided to give it a few more minutes. “Can you tell me anything she said about poetry?”