HARTFORD, Conn. — At 18, Katie Rose Fusco had found her voice.

The high school senior from Dutchess County, N.Y., was a talented artist who had just completed a portfolio depicting the struggles faced by women throughout American history. She also led a group of female students who petitioned the Dover, N.Y., board of education to change what they deemed a sexist dress code.

But Fusco also appeared eager to move on with her life: She had plans to attend Dutchess County Community College, then SUNY Purchase before launching her career in digital advertising. When she graduated in June of 2016, her mortarboard bore the phrase “Finally Out!”

She was living with her adopted family, but like many adoptees, Fusco was curious about her biological family and tracked them down through social media. In August 2016, instead of enrolling in community college in New York, she moved to Henrico County, Va., to live with her birth parents, Steven and Alyssa Pladl, and her two young sisters.

It was a journey that ultimately led to her death last week, and the deaths of her adoptive father, her biological father and her infant son in tragedy that spanned three states.

Police said Steven Pladl began a sexual relationship with Katie, his daughter, and she gave birth to their son in September. Four months later, both Steven, 42, and Katie, 20, were arrested by police in Virginia on charges of incest and adultery.

Last week, after Katie told her father that she was severing the relationship, Steven Pladl killed their son, 7-month-old Bennett Pladl, then drove north to New York and shot and killed Katie and her adoptive father, Anthony Fusco, as they drove in New Milford, just over the New York border, according to police. He then killed himself.

“We may never understand the mindset or motives of Steven Pladl, but we do know his actions have shattered the lives of countless people,” Lawrence Capps, chief of Knightdale, N.C., the town where Bennett Pladl’s tiny body was found inside a bathroom closet.

“We pray the families affected are able to find some measure of comfort and peace as they work to cope with this senseless tragedy.”

The family tragedy had a straightforward beginning. Katie was born in 1998, but Alyssa, then 17, and Steven, 22, weren’t ready to become parents, Alyssa told WTVR, a Richmond television station. So they placed their infant daughter up for adoption.

Katie was raised in Dutchess County by Anthony Fusco, an officer with the New York State Department of Corrections, and his wife, Kelly, who worked as a secretary for the town of Dover’s land-use department.

By all accounts, the Fuscos were devoted to Katie, an artistic child who began drawing at a young age. Initially, she recalled in a post on her online portfolio, “I copied my mother’s old drawings and would present her with each doodle, sketch and painting.” But soon her own talents blossomed and she became known around Dover High School for her spontaneous comic strips.

“A pen and something to draw on became a safe place for me,” Katie wrote. “Ink became my weapon against rules and regulations. There wouldn’t be a corner in a classroom or park that didn’t have a secret little character living on it. Ask an artist why creating is important to them and they won’t ever stop giving out reasons. To be short; for me, a life without art is no life at all.”

The Fusco family shared a small, gray trailer in a crowded park near an aging former psychiatric hospital, right off busy Route 22, which cuts north south through Wingdale, a compact, working-class hamlet of Dover.

Anthony Fusco, who went by Tony, had retired from his corrections post, and neighbors said he had recently been working a job in maintenance.

Those who lived in Wingdale described it as a sleepy community, linked to New York City by a commuter train. The opioid epidemic has hit the area hard, claiming the lives of more than a dozen residents.

Some neighbors in the trailer park said they did not know the Fuscos well, but the news of Tony Fusco and Katie Pladl’s death spread quickly. One neighbor, whose trailer sits at the only entrance to the park, said he would see the family come and go, sharing a wave. “They were good people,” said Jim Moore, who has lived there for about a decade.

Moore’s two daughters grew up with Katie, and one was on the cheerleading squad with her. Moore described Katie as a reserved young woman, and he never knew of any troubles with the family. “I watched the girl grow up,” he said.

Katie left New York in August and moved into a two-story house just outside Richmond, Va., with her biological parents, Steven and Alyssa Pladl. After about two months, Steven began sleeping on the floor of Katie’s room. A month later, Alyssa moved out, according to the affidavit prepared by police in Virginia for Steven Pladl’s arrest.

Police said Katie and Steven Pladl, father and daughter, became involved in a sexual relationship and made plans to marry as soon as Alyssa and Steven divorced. In May 2017, Alyssa Pladl learned of the relationship, and the fact that Katie was pregnant, by reading a journal kept by Katie’s younger sister.

In interviews with a Henrico County detective, Katie’s two sisters said Steven and Katie slept in the same bed. They were instructed to stop calling Katie their sister and instead refer to her as their stepmom. One of the girls said her father told her not to tell anyone about his relationship with his oldest daughter “or else her friends would make fun of her.”

Katie and Steven’s son, Bennett, arrived in September 2017. By then, the couple had settled in Knightdale, N.C., just east of Raleigh, and Katie had taken her biological father’s surname.

In January 2018, they were arrested at their home in Knightdale on a warrant from Virginia charging them with incest, adultery and contributing to the delinquency of a minor.

Media reports say both were released on bond after appearing in court in Virginia, and Katie went back to live with her adoptive parents in New York. Katie and Steven were barred from contacting each other and Steven’s mother had custody of their child.

The catalyst for last week’s tragedy came on Wednesday, when Katie Pladl called Steven from Wingdale and severed their sexual relationship.

The details were revealed in a frantic 911 call placed by Steven Pladl’s mother on Thursday morning: “My son just called me and he told me … he killed his baby,” said the mother, whose name has not released by police.

“I just got off the phone just a couple minutes ago, and he told me to call the police, that I shouldn’t go over there. … He said he put a key under the front mat, a key to get into the house,” she told a 911 operator in Cary, N.C., where she lives.

It is unclear when 7-month-old Bennett Pladl was killed. Police are not releasing the cause of the infant’s death, but say the child did not suffer from any noticeable injuries or trauma.

After killing his infant son, Steven Pladl headed north to Wingdale, N.Y., a drive of more than 500 miles. He called his mother around 8:45 Thursday morning and confessed to killing Katie and Anthony Fusco.

“His wife broke up with him over the phone yesterday. … He killed his wife. He killed her father,” Pladl’s mother told the operator.

Then, she added, “I can’t even believe this is happening.”

Police believe Steven Pladl was watching the Wingdale home from the parking lot of a neighboring liquor store.

When Katie Pladl and Anthony Fusco drove away from the home on Thursday, Steven Pladl followed them from Wingdale into nearby New Milford, until they reached a stop sign at routes 7 and 55, police said. It is unclear whether Katie Pladl and Fusco were aware at some point that they were being followed.

Witnesses told investigators that Steven Pladl’s minivan pulled along Fusco’s truck and that “several rounds” were fired from an assault-type rifle, similar to an AR-15, into the passenger side of the vehicle. Katie Pladl and Fusco suffered “multiple gunshot wounds to the upper torso and head,” New Milford police Chief Shawn Boyne said.

The bullet-riddled pickup truck in which Katie and her adoptive father died was sent to the impound lot behind the New Milford police station. A blue tarp covered the blood-spattered cab.

New Milford police, who continued to investigate the incident, said they learned Friday afternoon that that Katie and Anthony Fusco were on their way to Waterbury for Katie Pladl’s job cleaning her adoptive grandmother’s house. The grandmother told detectives she was surprised when her granddaughter failed to arrive as expected.

At 9:15 a.m., police in Dover found Pladl’s minivan. He was inside, and apparently had committed suicide, police said.