HARTFORD, Conn. (AP) – From grocery store aisles to gun shop counters, shaken Connecticut residents struggled to comprehend the seemingly random attack that left a mother and two daughters dead in their burning Cheshire home this week.

Many questions remain unanswered, among them what might have pushed two petty burglars to a night of kidnapping, rape, arson and murder.

“If you put two people, two certain people, together, they say it’s like mixing oil and water,” Cheshire police Lt. Jay Markella said. “Sometimes it gels perfectly together and things escalate. You mix the wrong chemicals, you get an explosion or you get nothing.”

Two parolees, 26-year-old Joshua Komisarjevsky of Cheshire and 44-year-old Steven Hayes of Winsted, remained jailed on $15 million bond each Thursday.

Prosecutors said they will seek the death penalty against the two, who were each charged Thursday with six counts of capital felony. They already faced charges of assault, sexual assault, kidnapping, burglary, robbery, arson, larceny and risk of injury to children.

A public memorial service has been set for Saturday for school nurse Jennifer Hawke-Petit, 48, and her daughters. Hayley, 17, planned to attend Dartmouth College to study medicine. Michaela, 11, wanted to be a gourmet cook.

Hawke-Petit was strangled and her daughters died of smoke inhalation as the house burned around them, according to autopsy results and police.

The lone survivor, Dr. William Petit Jr., was badly beaten but managed to escape. He remained hospitalized with serious injuries Thursday.

“He’s doing as well as can be expected under the circumstances,” said Petit’s brother, Glenn Petit. “Emotionally, he’s a mess. He is stunned right now. He’s had his family taken from him.”

The family had recently returned from a vacation to Cape Cod and had not even had a chance to develop their photos.

A police source close to the investigation confirmed reports that Komisarjevsky and Hayes spotted Hawke-Petit and one of her daughters at a local grocery store Sunday and followed their car home.

Police gave family members the same account, Glenn Petit said.

“They were attracted to the car,” he said, though he was not sure what model Hawke-Petit was driving. “They liked the car, followed her home, thought she lived in a nice house.”

Authorities say Komisarjevsky and Hayes broke into the Petit home early Monday and held the family hostage for several hours before forcing Petit’s wife to withdraw money at a local bank later that morning.

Suspicious bank employees notified police, who caught the suspects as they tried to flee.

Komisarjevsky and Hayes, convicted burglars with lengthy nonviolent criminal records, were out on parole when the attack occurred. They were roommates at a drug treatment center and halfway house in Hartford last year.

Some criminologists said Thursday that it is not unusual for two people to feed off of each other’s emotions when committing a crime together, ratcheting up the severity and viciousness.

“Oftentimes with someone else, you’ll do things you wouldn’t have the nerve or desire to do alone, and that’s why you’ll often find in these brutal cases that there’s more than one perpetrator,” said James Alan Fox, a criminal justice professor at Boston’s Northeastern University.

Louis B. Schlesinger, a forensic psychology professor at John Jay College in New York City, said in such cases, it also is not unusual for one suspect to have sexual motives and for the other to go along with it.

According to prosecutors, the younger girl and her mother were sexually assaulted.

“In most of these cases where there’s two offenders, you have one dominant person and one idiot he brings along,” said Schlesinger, who also has extensively studied criminals whose offenses escalate from voyeurism to burglary, sexual assault and sexual murders.

Komisarjevsky, the grandson of a renowned Russian theater director and a former dancer, lived a few miles from the Petits, but it was not clear if there was any connection between them.

His family released a statement Thursday, calling the crime “a monstrous, deranged act, beyond comprehension.”

“We cannot and will not condone anything the accused have done. Justice needs to take place,” the statement said.

Komisarjevsky was adopted as a child and was home-schooled by his parents, a religious couple with deep roots in Cheshire.

But by his early teens, he had started robbing houses in his hometown, according to court records. The crimes escalated and, within a few years, he bought military night-vision goggles so he could break in and steal items as his victims slept.

He told police that he robbed the homes to pay for drugs, but prosecutors said the escalating crimes were more calculating. A judge in 2002 called him “a cold, calculating predator” before sentencing him to nine years in prison and six years of special parole.

The crime has prompted the Connecticut Board of Pardons and Parole to review its policies.

Gov. M. Jodi Rell said Thursday she wanted an in-depth review of the state’s procedures for charging, sentencing and releasing criminals, saying the facts of Cheshire case should be “a touchstone” for the review.

It has also hit home with residents of Cheshire, a suburb of 29,000 people near Waterbury.

“This was brutal, it almost seemed to me that it wasn’t money they were coming after, that they were just angry,” said Noel Pasha, 54, who has lived in town for 15 years.

The owner of a local gun store said more people are also signing up for gun-safety classes so they can buy firearms.

“You talk to these people and you can see it’s hit home, this particular crime,” said Scott Hoffman, owner of Hoffman’s Gun Center in Newington. “It’s the sheer grotesqueness of the crime and the fact that it’s such a normal family.”