Erin Moriarty

Dr. Soulier was convinced that Daniel knew what he was doing when he committed the murders.

But despite Soulier's professional assessment, Daniel's defense team was determined to plead not guilty by reason of insanity.

And they planned to prove that the medications Daniel had taken made him that way.

The drugs made me do it.

The defense called Dr. James Marikangas to testify as an expert witness.

A neurologist and psychiatrist, he interviewed Daniel and his family members several times and reviewed Daniel's previous medical records and police statements.

Dr. Marikanga's testimony focused largely on SSRIs, a class of antidepressants that included medications that Daniel had been prescribed to treat severe depression.

According to Merrick Hengist, the side effect of those drugs could include extreme restlessness, outbursts of anger, and increased impulsivity.

Daniel, he said, was experiencing those side effects.

The doctor believed that Daniel had endured trauma for years, and that had in part made him more susceptible to dangerous side effects.

Daniel's father, Bill Marsh, also believed that Daniel's behavior was caused by medication.

You think that's the only reason why he killed Chip?

But isn't it just possible your son is a psychopath?

And why?

Why are you so convinced?

Most important, Dr. Marikangas said that on the day of the murder, Daniel had reported having an out-of-body experience.

Marikangas couldn't prove when Daniel's dreamlike state began or how long it lasted.

He just knew that according to Daniel, it had started sometime that night.

The doctor knew that Daniel, the defendant, had motivation to lie about this dreamlike state.

After all, Daniel hadn't said anything about it in his interviews with Special Agent Chris Campion or Dr. Matthew Soulier.