Bloodstains have been found all over the apartment of Mark and Lori Hacking (search), family and investigative sources told Fox News.

Police sources say that when they entered the Hacking apartment earlier in the week, it appeared to have been cleaned. But investigators detected a substantial amount of blood and blood drippings using the forensic chemical luminol (search), which can make traces of blood glow blue-green in the dark even if it has been cleaned up, sources say. Police say they believe the blood is Lori’s and that she was attacked in her apartment. Toxicology results that can confirm whether it is Lori’s blood are still pending.

Detectives meet privately with the Mark and Lori’s families earlier in the day. Homicide detectives usually inform family members in high profile cases before announcing pertinent information to the media such as possible suspects. Police have previously called husband Mark Hacking (search) a “person of interest” in the investigation, but have not declared him a suspect.

Police searched a municipal landfill with cadaver sniffing dogs earlier today, possibly searching for a discarded mattress. Mark Hacking reportedly purchased a queen-sized mattress a mere half hour before reporting his wife missing to police. Investigators removed a box spring from the couple’s apartment late Monday afternoon.

Lori Hacking, 27, was reported missing to Salt Lake City police on Monday morning by her husband who said she did not return from her usual morning run in Salt Lake’s Memory Grove Park and City Creek Canyon area. More than 1,200 volunteers began searching through the perilous terrain surrounding the city park and canyon for the five-week-pregnant Lori on Tuesday.

Mark Hacking has come under increasing scrutiny in the past few days after it was revealed that he had never completed college and was never accepted to graduate school. Family members of both Mark and Lori Hacking said they were surprised to learn that Mark had not graduated from University of Utah and had never even applied to the University of North Carolina, where they believed the couple was going to move so that Mark could attend medical school.

Family members have denied that Mark is in a psychiatric ward and on medication following a breakdown during which he was found running around a local hotel with nothing but sandals on Monday night. Mark was checked into University Neuropsychiatric Institute early Tuesday morning, but his current whereabouts are uncertain.

Family members are sticking by Hacking. Mark’s brother, Scott Hacking, told Fox News that he had spoken with his brother in the hospital.

“I looked my brother right in the eye and he told me he had nothing to do with it,” he said.

Investigators are not so sure; they have indicated that that they believe the investigation will be completed in a matter of days.

“We think he’s lying and we hope to prove it soon,” an investigative official told Fox News.

Fox News' Rita Cosby, Carol McKinley and C. Spencer Beggs contributed to this report.