DECATUR — When a successful engineer was on trial for gunning down a businessman outside a Dunwoody preschool, much of the focus was on the victim’s widow, who prosecutors suspected of having an affair with the gunman.

Four months after the gunman’s conviction, Andrea Sneiderman, 36, is accused of helping orchestrate her husband Rusty’s death, in part to collect the family’s property, money and a life insurance policy.

She was charged Thursday with malice murder, criminal attempt to commit murder, racketeering, two counts of perjury and two counts of insurance fraud.

Suspicion surrounded Andrea Sneiderman during the trial of Hemy Neuman, who was also her boss. Russell “Rusty” Sneiderman was gunned down in November 2010, moments after dropping the couple’s son off at a preschool in Dunwoody, a wealthy suburb north of Atlanta.

The trial included days of testimony on Andrea Sneiderman’s actions before and after her husband’s killing and whether she knew details of her husband’s death before she was told.

Phone records presented showed she and Neuman exchanged three phone calls on the eve of her husband’s death and that she called him six more times on the way to the hospital. She testified that she

didn’t know her husband had been shot until she reached the hospital about an hour after the shooting, though her father-in-law and a close friend both testified she told them he had been shot during calls made on her way to the hospital.

Andrea Sneiderman repeatedly denied an affair and denied knowing anything about the shooting. She said she was the victim of “masterful manipulation” from a stalker who weaseled his way into her life only to ambush her husband when she refused his advances.

Sneiderman’s attorneys issued a statement Thursday reiterating her innocence and promising a vigorous defense “to ensure that Andrea is fully exonerated of these false accusations.” Her attorneys include J. Tom Morgan, who spent 12 years as the DeKalb County district attorney.

At the time of Neuman’s trial, Rusty Sneiderman’s brother, Steve, said the family long suspected Andrea was involved in his death, and the trial only confirmed their suspicions.

The Sneiderman family said in a statement that Thursday’s arrest brought no joy but called it “another important step in pursuit of justice for Rusty.”

DeKalb County District Attorney Robert James declined to answer questions about the evidence, but the 19-page indictment alleged Sneiderman and Neuman were having an affair and conspired to kill Rusty Sneiderman with the intent of “acquiring property, money and life insurance proceeds.”

She received a full payout plus interest of $2 million in insurance policies on her husband, as well as control of $960,000 in various bank accounts, the indictment said.

“Neuman and Andrea Sneiderman conspired together to murder Rusty Sneiderman so that they could enjoy a life together, eliminate Neuman’s debt problems and fully benefit from the assets the Sneidermans had acquired as well as the proceeds of Rusty Sneiderman’s life insurance policies,” the indictment said.

The indictment also alleged Andrea Sneiderman gave Neuman her husband’s schedule “so that Neuman could kill Russell Sneiderman.”

When asked why prosecutors were pursuing the case now, James, the district attorney, said: “Now is because we are ready now. If we were ready three months ago, it would have been three months ago. If it was last year when we charged Mr. Neuman, it would have been then.”

Sneiderman was arrested Thursday at a home in Putnam County and was being held without bond. Details of an initial court appearance were not immediately available.

WSB-TV aired footage of Sneiderman dressed in shorts and a long-sleeve shirt surrounded by law enforcement officials as she left the house, was handcuffed and placed in a patrol car.

Neuman’s trial attracted international attention because of the brazenness of the slaying, the upper-middle-class backgrounds of the suspect and the victim, and the fact that it took place outside a day-care center.

Russell Sneiderman was a Harvard-trained entrepreneur who witnesses said was killed by a bearded man in a hoodie who fired four shots and then hopped into a silver minivan and sped away. It happened so quickly that police initially believed it could have been a professional job.

Neuman, a father of three who worked at GE Energy with Andrea Sneiderman, was arrested about six weeks later after prosecutors learned he had rented a similar vehicle before the shooting.

Prosecutors argued he meticulously planned the killing and that he didn’t show signs of emotional distress in the weeks leading up to it. But defense attorneys said Neuman was suffering from delusions, that an angel who looked like Olivia Newton-John ordered him to carry out the shooting and he believed he was the father of Andrea Sneiderman’s two young children.