The filmmaker Werner Herzog has been peering into death row recently for the film “Into the Abyss.” But some interviews were so intense and fascinating, they made for a four part series, “On Death Row” that started tonight on Investigation Discovery.

While it is the latest in a wide variety of films he’s made over his career, including “Cave of Forgotten Dreams,” “Grizzly man,” “”Fitzcarraldo,” “Woyzeck” and “Cobra Verde,” Herzog said at the TV Critics’ winter press tour there is an underlying thread.

“In all of my films, including feature films, I’ve always tried to look deep into the human condition. ‘Into the Abyss’ could have been the title of many of my films. So when I look into the cave, I look deep into prehistory of man, 32,000 years back, there were people who were almost like us and created magnificent art. I look very the vertical look, and this vertical look into the abyss of the human condition you’ll find in the Death Row project, you’ll find in ‘Aguirre: The Wrath of God’; you’ll find it in a documentary like ‘The Great Ecstasy of the Sculptor Steiner’ of a man who actually literally flies into abysses.

“So I’m not only stretching out horizontally, going all the way to the Sahara Desert or Antarctica and Alaska and Russia and whatever. No. I’ve always expanded my curiosity horizontally. But, in almost every single film, I attempt to look very, very deep into the abysses, and because of that, the ‘Cave’ film and the ‘Death Row’ project are not that far from each other.

In each instant, “I’m a storyteller, and I’m trying to tell a part of a story,” Herzog says. “I try to look very deep into our human condition, in this case, into the dark recesses of the human soul.”

Though he states it at the outset, Herzog tries to keep his own opinion on the death penalty out of it.

“I personally do have an opinion about capital punishment, and I let everyone know. It’s in the prologue of all of these films that I’m not advocate of capital punishment, but at the same time, as a German, I would not want to tell the American people how to handle their criminal justice. But, otherwise, the cases are so distinct from each other, and each story has something very particular about it that I do not really voice much about opinion about every single inmate that I’m dealing with.”