To his landlords, Richard and Janet Pershing, Robert Wilson "seemed like a normal sort of guy, kind of courteous," living a quiet life of romantic picnics with his girlfriend and shooting the breeze on the front porch of his rooming house here in what looks like a slice of Norman Rockwell's America.

But about 1 a.m. today, police moved in and the stunned Pershings discovered later that they had rented one of the three apartments in their red brick rooming house to a killer and master thief on the U.S. Marshals' 10-Most-Wanted list: Bernard C. Welch.

"He'd help the wife carry in her groceries, and he'd sit out on the front porch with the wife and I," said the gray-haired Pershing, a retired sales manager for Overmyer Mould Co. here.

" 'Course we probably wouldn't have sat out there if we'd known he'd killed somebody. How do you tell about a person anymore, anyway?"

Welch moved in June 19, telling Pershing that he had been working in Saudi Arabia and intended to take a year off. "I said, 'How ya going to pay the rent?' He said no problem, he'd made a lot of money -- in the six-digit figures. He peeled off $750" for two months' rent at $250 a month, plus a security deposit.

Pershing said Welch left twice on two-day trips -- one of them, Welch told him, to Washington, where cardiologist Michael Halberstam lived when Welch shot him to death in 1980. Welch was serving a 143-year sentence when he escaped May 14 from a Chicago prison.

Pershing's wife, Janet, a solid woman with gray hair and glasses, said Welch was always smiling and happy. Now she and her husband are in shock, she said: "I just don't feel anything. We've never had any contact with murderers . . . . It don't make sense really."

Welch met a local woman in her thirties "in a mall or restaurant" nearby, the landlord said, and the pair had sometimes sat with him on the porch. Although police later identified her as Janice Roos, Pershing said he did not want reveal her name because "she was just an innocent bystander. She was taken in by him just like we were . . . . She's of course in tears over the thing. She didn't know what she was dating."

He said she was a "thin gal, in her thirties, with light blond hair, a store clerk, who moved in with Welch a few weeks ago. 'Course the wife and I don't approve of live-ins," Pershing said. "Next lease we draw up, we're going to rule it out."

Welch and the woman went on drives and picnicked at Twin Lakes, a nearby recreation park, he said. They often stopped to chat in the back yard on their way to the Speedy Mart.

Welch's apartment, with sheer white curtains in the window, is one of the Pershings' 10 rental properties.

A yellow crime-scene ribbon sealed off entry to the apartment on the third floor of the rooming house today. U.S. marshals, FBI agents and local police passed up and down the rear outside stairway, the only entrance to Welch's apartment, which authorities said contained stolen jewels and weapons.

Janet Pershing shucked a pile of fresh corn and dispensed cherry Cokes to the reporters suddenly tramping en masse through the place. Between interviews, her husband worked in his vast garden of zinnias, daisies and tomatoes.

At the police station, the officers were still learning about their prisoner. Arresting officer Paul Burkey, a sudden celebrity sought after by the national news media, was at home in bed, his colleagues said, because he works the midnight shift.

Retired police lieutenant Larry Lucchetti, working the desk, said he had a call from author David Halberstam, brother of the dead cardiologist.

"He wanted to thank us for catching him," Lucchetti said.