The Manhattan doctor at the center of a town house collapse sent a rambling e-mail to his ex-wife that warned his ex would be "transformed from gold digger to ash and rubbish digger."

Meanwhile, police said Tuesday that a gas line leading into the doctor's Upper East Side town house was tampered with before the home was destroyed by an explosion Monday.

Police and fire investigators searching through the rubble of the 4-story building discovered that the basement gas line had been modified so a hose could be attached to it, said New York Police Department spokesman Paul Browne.

Someone stretched a hose from the line to the rear of the building, he said.

Dr. Nicholas Bartha sent his e-mail rant to FOX News, Sen. Arlen Specter, R-Pa., and others in the hours before the explision leveled his house. It was the latest in a series of implied threats from the emergency medicine specialist, who had taunted his ex-wife, Cordula Bartha, with swastikas, according to court records and police.

Click here to read Bartha's e-mail.

Authorities were investigating Tuesday whether the 66-year-old doctor might have caused the blast rather than sell the home as part of a divorce judgment in his ex-wife's favor.

Nicholas Bartha, who survived the blast and was pulled from the rubble, recently contemplated suicide in the rambling e-mail to his ex-wife:

"When you read this ... your life will change forever. You deserve it. You will be transformed from gold digger to ash and rubbish digger. You always wanted me to sell the house. I always told you I will leave the house only if I am dead."

The morning explosion hurled fireballs high into the sky and left the upscale block covered in bricks, broken glass and splintered wood. Authorities said at least 15 people were injured, including five civilians and 10 firefighters.

The doctor was rescued after yelling up to rescuers while buried in the wreckage, fire officials said. Bartha and one passer-by suffered severe injuries; the remaining injuries were minor.

"This could have been an even worse disaster than it already is," fire commissioner Nicholas Scoppetta said.

Scoppetta said authorities were looking into the possibility that the blast was the result of a suicide attempt, calling it "a distinct possibility."

The explosion and fire created a horrific scene on the Upper East Side. Heavy black smoke rose high above the 19th-century landmark on 62nd Street between Park and Madison avenues — just a few blocks from Central Park. Debris was strewn everywhere. Four of the injured were pedestrians — some of them found on the street covered in blood.

"In a few seconds, finished," said Thad Milonas, 57, who was running a coffee cart across from the building and came to the aid of two bloodied women. "The whole building collapsed."

Scoppetta said authorities were looking into the possibility that the blast was the result of a suicide attempt, calling it "a distinct possibility."

Bartha had recently lost a $4 million judgment in the divorce case, and court records paint the picture of a bitter dispute that dragged on for five years. The building that exploded was to be sold at auction in October to pay the judgment. The building was worth nearly $5 million based on a 2004 assessment and as much as $6.4 million in today's market. Before and during World War II, it was used as a secret meeting place by a group of prominent New Yorkers who informally gathered intelligence for President Franklin D. Roosevelt.

Bartha was served eviction papers on Friday, said Dr. Paul Mantia, who also worked in the building.

An attorney who represented Bartha in his divorce said his former client considered the house "his pride and joy."

"Faced with possibly losing it, he couldn't handle the pressure," Ira Garr said on FOX News Channel's "On the Record with Greta Van Susteren." Garr said he stopped representing Bartha after the doctor seemed to lose interest in pushing further with the appeal of his divorce judgment.

According to a 2005 appellate court opinion, the doctor had "intentionally traumatized" his Jewish wife, who was born in Nazi-occupied Holland, by posting "swastika-adorned articles and notes" around their home. The opinion also said Bartha had "ignored her need for support and assistance while she was undergoing surgery and treatment for breast cancer."

Cordula Bartha was granted the divorce "on grounds of cruel and inhuman treatment," according to the opinion, which also says her husband "systematically cut off her access to marital funds and credit as a means of psychological abuse."

In a petition filed this year by Cordula Bartha, she hinted at looming troubles and asked that deputies remove Nicholas Bartha from the residence. "I have no doubt that (Nicholas Bartha) will ensconce himself in the marital residence and refuse to leave it after the auction is held. He has said many times that he intends to 'die in my house."'

Cordula Bartha had moved out and was living with the couple's two adult daughters elsewhere in the city.

Attorneys for the 64-year-old ex-wife issued a statement: "Ms. Bartha cannot at this time withstand the additional burden of the media microscope on this personal tragedy. Ms. Bartha and her family are deeply saddened and terribly upset by today's occurrence."

The fire was reported at 8:40 a.m., and hundreds of firefighters rushed to the scene.

Power company Consolidated Edison said an employee had been in the basement of an adjacent building responding to a complaint about a smell of gas at the time of the blast. The employee was unhurt.

The utility had been at the Bartha building June 8 after a routine check found a gas leak on a pipe in the basement. The gas was shut off, and Nicholas Bartha was asked to get the pipe fixed, spokesman Joe Petta said. The gas was turned back on after the utility ensured the leak was fixed.

Rabbi Yaakov Kermaier, 36, a resident in a building next door, said he was outside when he heard "a deafening boom. I saw the whole building explode in front of me."

"Everybody started running, nobody knew what was coming next," said Kermaier, whose nanny and newborn escaped from their apartment unharmed.

The building housed two doctors' offices. Authorities said a nurse who was supposed to open one of the offices arrived late, narrowly missing the explosion.

Bartha was apparently the only person who lived in the building, Scoppetta said.

TV host Larry King, who had been in his hotel room nearby, described the explosion to CNN as sounding like a bomb and feeling like an earthquake. "I've never heard a sound like that," King said.

The building is in an upscale neighborhood where the 2000 Census put the median home price at $1 million. The area was once synonymous with high-society types like J.P. Morgan and William and Cornelius Vanderbilt.

The Associated Press contributed to this report.