But Marlatt did not believe it was an accident. And last week, in a Chatham, Ont., courtroom, the truth emerged. In front of his parents as well as Marlatt, Dewald, a 36-year-old widower, pleaded guilty to two charges of second-degree murder. Earlier, he recanted his story that his children drowned while he slept. He confessed that he held their heads underwater until they died - convinced that they were hindrances to reconciling with Marlatt. That conclusion, Marlatt recounted in a two-hour interview with Maclean's, arose from a conversation a month previously. Recalled Marlatt, a divorced mother of two young girls: "I told him I didn't enjoy being around Jennifer. She was needy and clingy. But I only told him this to get him away from me."

The revelation of the killings had an explosive effect on Leamington, the small, picture-postcard town of 15,000 people on the shores of Lake Erie where Dewald lived. But for some in the town, 10 minutes from Wheatley, there had been ominous signs before the tragedy. Dewald was a quiet but familiar figure, seen at local video stores, playing badminton and ordering takeout food. Some also knew him as a man who neglected and abused his children: Caroline Hall, a former neighbour, once saw Dewald throw Christopher across a room. Hall alerted Children's Aid. Many times, said Hall, Dewald left Christopher and Jennifer alone late into the night. Christopher would come to the Hall home to open a can of spaghetti or borrow bread to feed his sister dinner. Says Hall: "They were abused and neglected. It was tucked under the table."

Dewald, a tall, bookish-looking man with wire-rimmed glasses and receding sandy hair, was born in Windsor on Feb. 6, 1963. When Dewald was three, the family moved into a small detached cottage near Wheatley on the shores of Lake Erie - the same place where Dewald later killed his children. After graduating from high school in Leamington in 1981, Dewald worked at a local A&P store and later in Windsor. In 1984, on a vacation in Hawaii, Dewald met Nida Maheres, who was of Philippine origin, and the two immediately fell for each other. Dewald returned to Hawaii the following year and they were married. They lived briefly in Honolulu, where Christopher was born. Dewald returned to Canada alone to a job at the General Motors plant in Windsor. In 1986, Nida and Christopher joined Dewald and the couple moved next door to Dewald's father. Jennifer was born in May, 1988, and the family seemed happy. But in 1991, Nida became ill. She died of spinal cancer in 1992.

The children seemed to handle the death better than their father. He became depressed, took time off work and dated a series of women. Christopher was a shy but happy child, with a seemingly permanent smile. Both children were popular and well behaved, and everyone noted their closeness. At lunch at school, Christopher would run to Jennifer to make sure she had enough to eat. If not, he would give her some of his food. "Chris didn't ask for much, just a hug," said Marlatt. And, said Linda Morgan, whose son was a friend of Christopher: "Every time the children came to the door they were smiling and happy." But both Marlatt and the school principal had called Children's Aid to report neglect and physical abuse. A social worker, Andrea Lukos, visited the home. On March 12 last year, Christopher told her that something might happen to his father if he did not get help. Dewald had been admitted to Windsor Regional Hospital for depression and the children were staying with their paternal grandmother, Evelyn. After an investigation, Lukos concluded the children were at "medium" risk, but this could change when Dewald returned home. The last visit by a children's aid worker was on June 30, 1998. Dewald said that he was feeling "better," and had stopped taking medication.

Dewald might have escaped punishment if not for Marlatt. Police concede their only evidence was his confession to them last August, and one the previous day that had been recorded in Marlatt's home. Until last week, when a judge ruled against them, defence lawyers were contesting the admissibility of the confessions. In fact, police say Marlatt made the charge possible. "Without her we had nothing. She was willing to do anything we wanted," said Det.-Const. Joe Devolder of the Ontario Provincial Police, the lead investigator.

Marlatt first met Dewald in March, 1996, when her then nine-year-old daughter brought Christopher home, announcing that he was her boyfriend. Shortly after, the parents met and started having coffee. Marlatt said Dewald made her laugh and feel good about herself. Recently divorced, she felt bruised by the breakup. She liked Dewald's humour and was flattered by his devotion. "He was a totally different breed of man than I was used to," said Marlatt. "He was sincere and genuine." But doubts began. Dewald would call repeatedly, arrive on her doorstep right after work, and wanted to be with her all day. Then, there was his treatment of his children. They adored Dewald, but he seemed indifferent. Often, Marlatt had to tell him to go home to them.

Despite Dewald's neglect, there was little hard evidence of abuse, so people were reluctant to intervene. His late wife's relatives, who live in Las Vegas and Hawaii, pleaded with Dewald to send Christopher and Jennifer to live with them. "No matter what we had to do, we would have wanted them with us," said Robert Pauline, the children's uncle, in a telephone interview from Las Vegas. But Dewald made no effort to stay in touch - and never told the family of the deaths. They learned the news when Devolder contacted them during the investigation. Pauline told Maclean's that there were bad feelings, stemming from an incident in which Dewald threatened Pauline's wife, Adeline, during a visit to Leamington. Said Pauline: "My wife wanted to come home right away. She was shaking. I told him never to touch my wife again."

Meanwhile, as the relationship between Marlatt and Dewald continued, she felt increasingly uneasy. In March, 1997, she was admitted to hospital with a form of strep throat. Dewald hovered over her bed, discouraging visitors. "He wanted me to himself," said Marlatt. She decided to end the relationship, but they dated periodically until November. Then, Marlatt told him it was over and that she never wanted to marry him.

Dewald reacted in disturbing ways. On Dec. 11, 1997, she caught him peering in her window while she and her children ate dinner. That night, one of Marlatt's daughters found him in their backyard, lying in the snow in a fetal position. He had overdosed on antidepressant pills and aspirins. Dewald spent 72 hours in hospital. "I was worried. I cared about him," says Marlatt. But she wanted him to go away. Marlatt moved, and did not tell him her new address. Dewald drove by every house in town until he found her car. Still, Marlatt did not fully reject him: "I know it seemed wrong, but sometimes I talked to him. We were friends. I liked his company. I felt sorry for him."

Marlatt often told Dewald she was concerned about his neglect of Jennifer and Christopher and his poor money handling. (Though he had a job at a division of General Motors as a sewing technician before the murders, Dewald was forced to declare personal bankruptcy and lost his home.) Undaunted, Dewald pursued Marlatt vigorously. She periodically caved in, agreeing to coffee or a chat. Last July, Marlatt decided on a new tack. She told Dewald that she did not enjoy Jennifer's company, presuming that he would not choose her over his children. Before that, Marlatt talked several times with two of her sisters about that approach. One sister, she said, warned that "if you tell him this, within two weeks, we'll pick up the paper and find two Leamington kids dead." Marlatt could not believe that someone with whom she had been so intimate could commit such an act. But when she made her remarks about Jennifer, Dewald was more subdued than she expected. "If it was me, I would have said 'there's the door, see you,' " says Marlatt. But he said: "I understand." After that, he often raised the subject. "How can you hate Jennifer?" he would say. "She's just a little kid."

On Aug. 12, Dewald came to her house. He paced, and complained about single parenthood. She recalls him saying, "I don't enjoy being around my kids. I can't handle them right now." Dewald showed photos he took during a trip to Tobermory, Ont., a scenic area he wanted to visit with her. Marlatt was disturbed. She could not recall Dewald ever before taking photos of his children. In them, the two are perched beside a steep cliff. "thought to myself," she recalls, "he took them there to kill them."

The next day, he did so.

As soon as Det.-Const. Devolder took over the case, he was troubled. The day of the drownings was sunny, the water calm and the children were good swimmers. Dewald's story didn't sit well. Nor did his description of how he retrieved the children from the water. And the water was too muddy to see bottom, but Dewald knew exactly where to find Christopher's body. "For me," said Devolder, "in an area where both kids swim regularly, both could have drowned while one was saving the other. But there were no marks to indicate this."

Devolder's suspicions increased when he discovered that a week after the deaths, the children's belongings, including mittens, lunch pails, clothing and even condolence cards from the funeral, had been thrown in the garbage. "No parent who has lost his children is able to see their children's belongings discarded so callously," said Devolder.

After visiting Dewald on the night of the murder, a fearful Marlatt contacted police. Two days later, she sent her children to her ex-husband. Marlatt allowed police to wire her home and agreed to meet Dewald several times over the next two weeks to try to extract a confession. In one session, Dewald gave Marlatt a photograph of the children with a message on the back: "To Tina - In loving memory of Christopher and Jennifer Dewald. They will be missed. Love Tom."

Marlatt and the police staged meetings at her house, knowing that Dewald would drive by and see them. Marlatt told Dewald that the police were asking questions about him. On Aug. 28, she said: "Police think I'm part of this. Tell the truth or get out. Without me, you have nobody." Then, she asked: "Did you do it ?" Dewald held up a hand, gesturing for time. Marlatt asked the question again. He nodded, mouthing inaudibly: "Yes, I did." Then, Marlatt asked: "Did you kill them together or separately?" He crossed two fingers. Later, when Marlatt asked why, he said, "Because I love you more than anything else in the world."

The next day, Dewald confessed to police. He implied that circumstances - his wife's death, the pressures of being a single parent and his bankruptcy - drove him to kill them. He did not want them to lead a life like his own. "Life sucks, you know," Dewald said in his confession. "My kids gonna have to go through the same shit."

Until last week, Dewald planned to enter a not guilty plea while lawyers awaited the ruling on admissibility. When a judge ruled they could be introduced in evidence, Dewald pleaded guilty to two counts of second-degree murder. Both charges carry life imprisonment.

The graves of Jennifer and Christopher, adorned by bouquets, lie side by side and at the foot of their mother's resting place in Erie Cemetery. They are about 400 metres from the home where Dewald grew up, and where they died. A dirt road winds around the graveyard, where deer find refuge and waves lap at the shore.

Dewald and Marlatt have not spoken since his confession. During her interview in her third-floor Leamington apartment, Marlatt smoked, drank black coffee and sat crosslegged on the floor, often stifling tears. The silence was filled at one point with the mournful song Ordinary Love by the singer Sade, with its too-appropriate lyric "I keep crying, I keep trying for you."

Dewald, Marlatt knows, would do anything to ensure that they were linked together. She no longer sees that as selfless devotion. Says Marlatt: "He did whatever he could for himself. At first, I felt compassion. Now, I think he's an animal." But in one way, she knows he achieved his goal: she will never again be able to put him out of her mind.