United for the first time, the family of the man who confessed to fathering seven children with his daughter celebrated the birthday of one of the kids, police said Wednesday, as they pieced together details of the family's ordeal.

Investigations remained focused on the crime attributed to the suspect by his own confession and DNA testing — the confinement of his daughter for 24 years to a basement dungeon where she raised six children he sired. A seventh child died in infancy.

But police suggested they were also looking into possible links to other crimes.

Alois Lissl, the chief of police of Upper Austria province, told The Associated Press that, although no evidence had surfaced so far, police have widened their investigation into an unsolved murder 22 years ago to include the incest suspect because he could have been in the area at the "time and place" of the killing.

The bound body of Martina Posch was found on a shore of the Upper Austrian lake of Mondsee on Nov. 12, 1986. The wife of the incest suspect owned part of an inn and camp ground on the other side of the lake then.

"We have found no sign" of a concrete link up to now, Lissl said in a telephone call from Linz to the AP's Vienna bureau. Still, he said, the incest suspect would be asked for an alibi because the property owned by his wife could mean he was in the area when Posch was killed.

"We are looking at the case from a third angle," he said of the new direction his murder probe had taken.

Still, Lower Austrian police said the main focus of the ongoing investigation was to clear up what Josef Fritzl did to his daughter, Elisabeth, in the dungeon.

Click here to see photos of Josef Fritzl and the "House of Horrors."

"From the point of view of investigators in Amstetten there is no reason to see Josef Fritzl as the main suspect for a murder in Upper Austria," said police Col. Franz Polzer.

Police refused comment on other reports that Fritzl had a police record that had been erased under Austrian law because of the passage of time.

Asked about the allegations, Polzer, who is helping lead the investigation, said: "I can neither confirm nor deny it." But police and justice authorities said Fritzl's past would be examined thoroughly.

Medical personnel in Lower Austria, meanwhile, fought to save the life of the young woman whose hospitalization triggered the discovery that her family had been imprisoned and terrorized for decades. And authorities weighed the future of her five siblings.

Kerstin Fritzl's condition was critical but stable, authorities said. The 19-year-old is one of the children Josef Fritzl says he fathered with his daughter Elisabeth.

Kerstin, who is in an induced coma and on a respirator, is undergoing dialysis because of the effects of lack of oxygen. She was brought to the hospital unconscious and later suffered seizures. The fate of her family came to light after doctors, mystified by her ailment, appealed for her mother to come forward because they needed her medical history.

The other dungeon children appeared to be doing relatively well.

Berthold Kepplinger, director of the clinic where most of the victims are recovering from their ordeal, said the family members were "talking a lot" with each other and that they even celebrated an impromptu birthday party Tuesday for one of the kids, a 12-year old, complete with birthday cake.

"One already gets the sense that the family is doing well under the circumstances," Kepplinger said, considering that those born and raised in the cellar had to get used to normal everyday conditions, such as daylight.

The youngest, 5-year-old Felix, was "very affectionate" and does not stray from his mother's side, he said.

Elisabeth and her mother, Rosemarie, were also "getting along very well," said Kepplinger, adding that his staff was trying to create the conditions for "the best possible start into their new life.".

Kepplinger said Elisabeth and her children had the run of a closed-off part of his clinic.

Authorities were providing little information about Josef Fritzl, 73, who they say has confessed to locking up daughter Elisabeth since she was 18 and repeatedly raping her. He said he incinerated the body of one of their children who died in infancy. But since his initial confession Monday he has stayed silent on what authorities said were his lawyer's instructions.

Leopold Etz, chief of homicide investigations for Lower Austria province, said authorities were confident that Fritzl acted alone.

"I think we can rule out accomplices," Etz told the AP.

He said DNA tests confirmed that no other man entered the soundproof cellar rooms Fritzl made into a prison below his home. On Tuesday, tests confirmed Fritzl as the biological father of his daughter's six surviving children.

Fritzl led his wife, Rosemarie, to believe that Elisabeth had run away to join a religious cult when she disappeared, and authorities say there was no evidence that Rosemarie knew what was going on.

Elisabeth "never said that her mother was in the cellar," Etz said.

Fritzl brought three of the cellar-born children into his home, registering them officially as Elisabeth's abandoned children, but kept three more with their mother, cut off from the outside world. All, except Kerstin, have since met as a group with their mother and grandmother in an "astonishing" scene at a psychiatric clinic, authorities said Tuesday.

The father faces up to 15 years in prison if convicted on rape charges, the gravest of his alleged offenses. However, prosecutors said Tuesday they were investigating whether he can be charged with "murder through failure to act" in connection with the death of the infant. That is punishable by up to 20 years in prison.

Polzer, lower Austria's top criminal investigator, said one detail Fritzl had divulged — that the heavy steel door shutting the basement dungeon off from the outside world had a timer allowing it to be opened if he was away for a protracted period — was being checked on.

Amid the sordid details, precious little has been revealed about Fritzl's life or what led him to commit such a crime.

He was born April 9, 1935, in Amstetten, a working-class town 120 kilometers — or 75 miles — west of Vienna. He owned a number of properties in the region and paid his dues at the fisherman's club. Besides that, most neighbors or townsfolk remember only an affable, if unremarkable, fellow.

"Who is Josef Fritzl?" state broadcaster ORF asked in an online article. "All of Austria is asking this question, if not the entire world. What type of life did he previously lead, where did he work, how did he appear in public?"

It compiled a brief biography:

After mandatory schooling, Fritzl studied electric engineering at a polytechnic school and got his first job with steel company Voest. From 1969 to 1971 he worked for a construction material company in Amstetten, where he gained a reputation as an intelligent worker and a good technician. Then he went into the service industry and took over an inn 15 years ago.

Etz told the AP a police team was investigating Fritzl's past, saying it could take weeks to develop a clearer profile.

Kepplinger, the clinic head, said Elisabeth has spoken "quite a lot" about what she went through in captivity, but he declined to provide details. "It was definitely dreadful for her and for her children," Kepplinger said.

The case started unfolding on April 19 when Kerstin was found unconscious and was taken to a hospital. After receiving a tip, police picked up Elisabeth and her father on Saturday. Fritzl freed the captive children the same day.

One remaining question is who provided the tip. Authorities have declined to comment, but the daily Kurier said it was a senior doctor at the hospital to which Kerstin was admitted who sensed something strange about the family.