Lisa Stebic has been missing for more than five weeks and while police continue to question people about the whereabouts of the mother of two, there's one person who they can't get any more information out of: Her husband.

"Based upon the fact that his lawyer indicated that his client no longer wishes to discuss matters with the police, we really have no contact with him at this juncture," Plainfield, Ill., Police Chief Donald Bennett told FOXNews.com on Thursday.

Asked whether that was hindering the investigation, or whether police had gotten all the information they could out of Craig Stebic in the days after Lisa disappeared, Bennett said: "Any time an individual that’s very close to the person who’s missing that doesn’t share all the information with law enforcement, obviously it hampers our ability to look in certain areas we would have looked at with that information."

Lisa Stebic disappeared the night of April 30. Her estranged husband, Craig, says he was in the backyard of their shared house at the time, and the couple’s two children were out at a nearby store. Craig Stebic told police he assumed his wife had gone to the gym as usual.

Police also have not spoken to the children — 12-year-old Alexis and 10-year-old Zachary — since just after their mother vanished, Bennett said. Police attempted to set up a neutral location at a local child advocacy center with child experts on hand during the questioning, but Craig Stebic’s attorney refused the offer, Bennett said.

Craig Stebic's attorney also so far has advised him to refuse a polygraph test.

And without breaking the law, there’s little police can do at this time to force them to talk, since "the options that are available to you under the Constitution" are few and far between, Bennett said.

So police are reinterviewing many people they already talked to. But whereas the first time around, police were exploring the possibility Lisa Stebic ran off on her own, they now consider it a type of abduction case.

"We do not feel at this point she simply walked away," Bennett said, adding that the investigation has expanded into some areas he can’t give details on.

"The initial investigation was focused a lot on the missing persons of someone and we looked at areas we would normally look when someone’s missing and the … circumstances surrounding that," Bennett said. But that produced no solid leads that helped track Lisa Stebic down.

But now, Bennett said, "we are looking more at the fact she didn’t leave on her own accord and with that, we just have to start expanding our investigation into areas we weren’t in that before."

Police have also questioned a man Lisa Stebic had gone on several dates with — one of which was just before she disappeared.

"We’re talking to everyone but right now we have nothing to lead us to believe the individual has anything to do with her disappearance," Bennett said of that man.

Meanwhile, according to a Naperville Sun online poll Monday, almost 75 percent of respondents say police will be able to solve the case. Of the 411 votes cast by Monday, 304 voters said the case will be cracked, while 107 said it will not.

Click here to read The Naperville Sun story about the poll

Police have executed at least three search warrants on the Stebics' home. Although Craig and Lisa Stebic were in the middle of a divorce and hardly spoke, they lived in the same home. Craig Stebic has not been named a person of interest or a suspect in the case.

Last month, a bloody tarp was found in Craig Stebic’s truck. DNA tests confirmed that the blood on the tarp was his wife’s; Craig Stebic said it was animal blood. A cabin in that state owned by Craig Stebic’s father also was reportedly searched.

The state attorneys office has told police to not comment on aspects of the investigation such as the tarp or search warrants.

There are seven Plainfield police detectives working the case, with the aid of the FBI, Bennett said. An FBI spokesman told FOXNews.com he could not confirm nor deny any agency involvement with the case.

Lisa Stebic’s family announced this week that the reward for information leading to the safe return of Lisa is now $50,000. They are setting up a fund for donations to be made in her name for her children’s college education.

"I think we have to maintain thoughts that Lisa’s still alive until we can find otherwise. That’s why we’re still putting the resources necessary to try to narrow down our focus," Bennett said. "I would say the investigation has progressed from when it started — we certainly eliminated a lot of theories and a lot of speculations … [but] there’s still some ‘what if’ situations out there."

The June 18 issue of People magazine features an article on the missing mom. Her family is encouraging people to buy copies and put them in doctors’ offices, hair salons, gyms and other heavily trafficked areas.

Lisa Stebic is 37 years old, is 5 feet, 2 inches tall, weighs 120 pounds and has brown hair and brown eyes. She has two visible tattoos, a small rose on her ankle and a large butterfly on her lower back.

Anyone with any information as to her whereabouts should call the Plainfield Police Department at (815) 267-7217. More information is available at http://www.findlisastebic.com.