ARUNKUMAR Ingle never knew that he allegedly was being watched for four years by the very people he once watched over.

Ingle's children, Parth, 22, and Avnee, 25, were charged Tuesday in Delaware County with repeatedly hacking into their dad's e-mail account and tracking his whereabouts with concealed GPS devices in his cars.

It was only when Arunkumar Ingle, 55, was discovered beaten and stabbed to death inside his Middletown Township home on Jan. 21 that the alleged spying came to light through state police investigations.

The Ingle children were convinced that their father was leading a double life that involved extramarital affairs, including one with a Russian woman named "Anna," according to court documents.

On Tuesday, 10 months into the open murder investigation, Parth and Avnee Ingle were each charged with more than 450 computer crimes - including interception, disclosure or use of an electronic communication and unlawful use of a computer.

State Trooper Robert Kirby, the lead investigator, said that the Ingle children showed "no emotion" at the arraignment.

No one has been charged with their father's death, but Kirby said he was "very confident" an arrest would be made.

"This was not a random crime," he said. "We're not revealing anybody as suspects, but Mister Ingle was killed definitely by someone he knows - well."

Arunkumar Ingle's slaying was the third of 37 so far this year in Delaware County - more than half of them unsolved.

His body was found, beaten and stabbed in the head and neck, on the blood-splattered floor of his bedroom by his wife, Bhavnaben Ingle, who ran out of the house screaming, according to court documents.

Avnee Arunkumar told police that her dad had ordered everyone out of their home on the day before the killing for a meeting he was to have, court documents said.

Police said Avnee Ingle had told them that she attended a party in New York that day and that her brother picked up their mother to stay at his house in Pottstown overnight.

The next day, Avnee Ingle said, she picked up her mom at her brother's house and drove her back home, where her mother discovered her father's lifeless body, the affidavit said.

Avnee Ingle told investigators that her parents' relationship was on the brink of separation or divorce, and that her dad had spent nights in the bedroom while her mother slept on the sofa, according to court documents.

Parth Ingle told police that he learned of his father's infidelity from his mother in 2003, the documents said.

A year later, he installed keystroke-capture software on his father's computer that allowed him to obtain e-mail passwords so that he could "track his father's activities and whereabouts," the affidavit said.

The e-mails were viewed and accessed by both siblings with their mother's knowledge, Kirby said.

Court documents imply that Arunkumar Ingle had multiple affairs, but only one is identified by his children in court documents - a relationship with a Russian woman in Philadelphia named "Anna."

Avnee Ingle told police that she and her brother were tracking that relationship to keep tabs on whether he gave his mistress any money, according to the affidavit.

The children allegedly showed up at the Northeast Philadelphia home of their father's paramour in October 2007. Their dad spoke to them through a screen door before they eventually were forced to leave when his mistress called the police, court documents said.

Kirby said that the Russian mistress has been interviewed and is not a suspect in Ingle's death.

According to police, Bhavnaben, Avnee and Parth Ingle now live together in Pottstown, Montgomery County, while the house in Middletown, where neighbors estimated that the family lived for at least six years, is vacant.

The quote on Parth Ingle's MySpace page, which was last updated in August, reads "Boredom has struck!"

In his bio, he writes that he works in real-estate investment and is "most likely the coolest person you will ever meet."

His photo section consists only of a single picture of himself and numerous pictures of his automobiles, including a Nissan 350Z, a Nissan 300ZX TT and a Suzuki Hayabusa motorcycle.

"We don't know where the family is getting their money, but it's obvious from the cars Parth has been driving that there's money somewhere," Kirby said.

Following arraignments, Parth Ingle was released on 10 percent of $100,000 bail; his sister was released on 10 percent of $25,000.

Calls yesterday to the attorneys for both siblings and the attorney for their mother were not returned. *