In March, John S. Kristofak was under court supervision on a drug charge and was also harassing his ex-wife, Donna. At one point, he warned her “you are in danger – protect yourself. No one can help you at this point.”

Last weekend, police say, Kristofak made true on his threat, allegedly killing her in her Cobb County home. He is now the focus of a manhunt.

Kristofak, 58, a failed entrepreneur who ran a cell phone business and then a mortgage company, was jailed this year for several months on multiple charges of aggravated stalking. He pleaded guilty in October and was sentenced to seven months times served, with the rest of a five-year sentence to be served on probation.

Police are not releasing much about Kristofak or the couple’s stormy breakup, and county officials were hard to find for comment Monday because of the holiday. But court records indicate that Donna Kristofak, who was 48, filed for divorce in August 2011 after 19 years of marriage. In the filing, the mother of two teen-aged boys, who served as he own lawyer, asked that she get her old name back — Donna Jean Nations.

But it was not a clean break. The next month she filed for a restraining order against her ex-husband.

Her sister, Kathy Nations, called Donna “a dear sister who will be dearly missed,” but added little in the way of details. “We don’t want to say anything to interfere with the police,” she said. “But we’re glad the media is involved and his picture is everywhere.”

The Kristofaks’ union, at least on the outside, seemed happy. The family lived in a prosperous neighborhood, he headed a company called Metro Mobility Cellular and Donna was even featured in a 1995 newspaper article where pregnant women gave fashion tips.

In 2003, John Kristofak started East Cobb Mortgage during a real estate boom and the family lived in a home valued at nearly $500,000. However, the couple filed for bankruptcy in 2007, saying that they had three mortgages on their home and had a family income averaging less than $20,000 a year. He dissolved the mortgage company in 2008.

Things then apparently unravelled at a rapid rate. After the 2011 divorce and restraining order, Kristofak faced felony drug charges and agreed to a guilty plea in February, according to court papers. He was to be confined for eight months but allowed to be released to go to work.

But although he was apparently supposed to be serving jail time and under court supervision, Kristofak started repeatedly harassing his ex-wife.

Between March 9 and March 19, Kristofak “called the victim’s place of work 12 times and used vile, vulgar language to her and her coworkers,” according to a warrant for his arrest signed March 28.

The warrant also accused Kristofak of sending an e-mail to Donna on March 19, that read, “you are in danger – protect yourself. No one can help you at this point. You won’t know where it is coming from.”

Four minutes later, another e-mail read, “I warned you never cut me off from my children. You did and you will pay,” according to the warrant. “I am not living past tonight so I will do anything to get you back.”

Minutes later, another asked, “Have you ever been hit by a car going 140 not knowing where it’s coming from?”

Later, John Kristofak allegedly advised his wife in an e-mail to “make your final goodbyes with your children.” He then allegedly tacked posters to a tree in front of her house accusing her of “vile, vulgar sexual things,” the warrant states. One of her sons found the posters.

John Kristofak was arrested on the first warrant on March 29 after he allegedly followed his ex-wife to a Walmart parking lot, and “at one point pulled his vehicle in front of Donna’s in an attempt to stop her from leaving.”

In August, a magistrate set his bond at $250,000, although it is unclear whether he was released before the October guilty plea. With the plea, Kristofak agreed to a psychological evaluation, to not drink alcohol and to permanently stay away from his ex-wife.

He was also accorded first-offender status, as he had been eight months earlier.

Police were called to Donna Kristofak’s rented Cobb home late Saturday morning and found her unresponsive. She was taken to Wellstar Kennestone Hospital, where she later died of her injuries, according to Cobb police spokesman Michael Bowman.

John Kristofak remained at large Monday evening. Police say he is armed and dangerous. He faces charges of aggravated assault and murder, and was last seen driving a brown Chevrolet Equinox with Georgia tag BUV 2635.

Police ask that if anyone sees John Kristofak, they call 9-1-1 immediately. Anyone with information that could assist investigators is asked to call (770) 499-3945.