VALLEY CITY, N.D. (AP) - Authorities have narrowed the time of the killing of a Valley City State University student after getting a tip, Police Chief Dean Ross says.

Police now believe Mindy Morgenstern, 22, of New Salem, was killed sometime between noon and 3 p.m., on Sept. 13, Ross said. Earlier, they were looking at a period between noon and 9 p.m., when Morgenstern's body was found by friends in her off-campus apartment.

Police said Morgenstern died of a knife wound. They are still looking for suspects.

"If anybody saw anything in that area (around her apartment) between noon and three o'clock they should get hold of us," Ross said. "If they just think of anything that they saw that wasn't quite normal - whether it was someone driving home for dinner, passing in from the lake (Ashtabula). It's a heavily a traveled street - that's 5th Avenue - it was newly constructed this last year. Lots of people use it."

Ross refused to say what kind of a tip helped narrow the time frame, but he said it came after he made a public plea for help on Monday.

"I think if we wouldn't have put that (request) out there, then this individual would have still have sat on this information, which is very critical to the time frame," Ross said.

Funeral services for Morgenstern were held Tuesday in her home town of New Salem.

A ball sat in the hoop above pastors' heads at the funeral in the high school gymnasium, the strings of the hoops knotted to keep it in place.

Morgenstern's brother-in-law, the Rev. Jason Young, prayed for guidance for investigators as they tried to solve this "horrible thing."

Michael Morgenstern, who recently returned from Iraq, described his sister as someone who cared about others. He said she was going to be a bridesmaid in his upcoming wedding.

Valley City police gave the clergymen who spoke at the funeral Morgenstern's two Bibles. In one, she had written a spiritual "to-do" list.

The Rev. Ruger Winchester read one item from the list: "Make a prayer journal of the prayers you pray, and see how God answers each and every one of them, and blesses you."

The Rev. Doug Wyatt said Morgenstern had marked Psalm 23 "in bright, obnoxious green highlighter."

"She wanted us to know, the Lord is our shepherd," Wyatt said.

At a memorial service Monday at Valley City State, the school's president, Ellen Chaffee, said students and community residents are trying to help each other. She asked them to turn on a light each day as a tribute to Morgenstern and a message of hope, love and safety.

"I don't know how many of our lives could withstand the kind of scrutiny that Mindy's life is getting right now," Chaffee said. "They're doing all this investigating and they're not finding anybody with the slightest motive. I just think it's a tribute to the kind of person she was."