Wichita ? By day, the hunt for the BTK serial killer consumes Lt. Ken Landwehr. At night, though, pacing a dimly lit classroom, he simply refers to it as “that case I can’t talk about.”

Landwehr, the man now at the head of the investigation into a series of killings in Wichita in the 1970s and 1980s believed to have been carried out by the same murderer, spends his Tuesday nights teaching a Wichita State University class on serial killers.

Through the course of an evening session, filled with about 100 students — some just curious, others working toward a career in criminal justice — Landwehr shares thoughts shaped by a career investigating homicides.

On picking this city to carry out killings: “Wichita is a much easier hunting ground. It’s much easier to be anonymous.”

On the difficulty in finding BTK: “In the early 1970s and even the 1980s, it was difficult. We were not very aware of serial killers, especially in the Midwest.”

On the role of the media: “The experts talk about what the press knows. And they know very little of the information.”

Landwehr speaks vaguely of BTK. He used to focus one lecture on the case, but removed it from the class two years ago because it remains unsolved.

The lieutenant has been on the case 20 years and often teaches his class from a room that may have a link to it.

Room 218 of Hubbard Hall is where the late P.J. Wyatt taught an American folklore class in the spring of 1977. Landwehr announced a possible connection between the killer and a poem used in that course in a news conference last month.

In a series of letters signed BTK — which stands for “bind, torture, kill” — the killer has claimed responsibility for eight deaths. The communications had stopped for more than 20 years before resuming this year.

As the three-hour class continues, students see graphic photographs of decomposing bodies and crime scenes.

“If you’re there, it’s going to be disgusting,” Landwehr tells the class. “Trust me, I’ve been there.”