As a small Catholic community in Boise, Idaho, was preparing for the Christmas season in December 1982, a man sitting in the back of the church collapsed.

First came the stunned churchgoers surrounding the lifeless body lying under a pew. Then came the rustle of investigators scouring the man’s belongings for any clue they might present.

Could the silver and turquoise bolo tie around his neck mean he had come from the Southwest? Did the empty wallet, still bearing faint indentations where cards once sat, mean he wished to hide his identity? Was his dyed hair a disguise? And why was he carrying 29 keys attached to two metal rings?

The man didn’t look like he had been living on the streets, investigators thought as they pointed to his neatly filed fingernails and pressed pants. His deep, even tan also suggested he had been spending time somewhere other than frosty Idaho.

As questions piled up, investigators reached a single, clear conclusion. The man had come here to die.

He had $1,900 in cash and a typed note with instructions for his final arrangements, signed with a fake name, William L. Toomey. A coroner later determined the stranger had been poisoned by sodium cyanide, a highly toxic and fast-acting chemical compound.

At the time, the word “cyanide” was top of mind for many people in the United States. A few months earlier, seven people died in the Chicago area after ingesting Tylenol Extra Strength pills laced with potassium cyanide. Their deaths prompted one of the largest recalls in the nation’s history, and soon officials mandated tamper-proof caps on medication bottles and criminalized tampering with consumer products.

While many across America turned their attention to the widespread investigative effort to solve the Tylenol murders, the Ada County Sheriff’s Office worked to uncover Boise’s own mystery: Who was the “Unknown Wanderer”?

Both cases remained unsolved for decades. But now, a trail of breadcrumbs strewn across multiple states has led investigators to consider whether the two mysteries have always been intertwined.

The mystery of the “Unknown Wanderer” captured imaginations for years. In Boise, hundreds attended the nameless man’s funeral a few days after Christmas. The case reached a national audience when it was featured in a 1990 episode of the hit documentary series “Unsolved Mysteries.”The case went cold for decades after the Ada County Sheriff’s Office worked to identify the man to no avail.

That changed when Detective Tim Cooper, who watched that episode as a child, had a chance encounter in 2018 in the Sacred Heart Catholic Church parking lot.

He was drinking a cup of cheap gas station coffee when a parishioner approached him and started discussing the case, sparking his curiosity. Cooper got to work.

“He’s a smart guy. I mean, he tricked us for 43 years now. I knew he didn’t want us to know who he was. I knew he didn’t want us to know how he died. He didn’t want us to know a lot of things, and that, in itself, was a mystery that we needed to solve wherever it took us,” Cooper said in a new “Unsolved Mysteries” episode featuring his investigative efforts.

The detective approached the challenge as he had other cases. “He stumbles upon something and then starts drawing little red threads in his brain that connect the dots,” Ada County Sheriff Matt Clifford said.

When reviewing nearly 17,000 missing persons reports left him with no leads, Cooper turned to the 29 keys that had been sitting in an evidence room for decades, collecting dust.

With the help of a magnifying lens and the trained eyes of Boise’s key experts, Cooper took a closer look at the small, jagged pieces of metal and found a hallmark in one of them, indicating it had been purchased at a hardware store in Jacksonville, Florida. Then, two words etched into its surface gave him a street name: Mills Court.

As he looked into who had lived in the cul de sac, which had fewer than a dozen homes in the 1980s, Cooper learned one of the residents had gone missing and was declared dead in absentia. A DNA test volunteered by the resident’s brother in Los Angeles gave Cooper a definitive answer.

The “Unknown Wanderer” had a name: Matthew Francis Betkowski.

From privileged beginnings to a promising career marred by mental health struggles, a picture of Betkowski’s life began to unfold.

“By all accounts, he was a brilliant man, but he struggled to connect with people in life,” Cooper said about Betkowski when law enforcement announced the identity of the “Unknown Wanderer” last month.

Betkowski, who was 39 when he died, was born to a prominent Southern California family, helmed by a father who worked as a senior Los Angeles Department of Water and Power official and a grandfather who served as president of the Los Angeles City Council, at times serving as mayor.

As a child, Betkowski displayed a morbid curiosity with chemicals and explosives, Cooper learned. He once built a makeshift bomb with his brother, putting the life of another child at risk with the shrapnel from the explosion. His high school friends spoke about how he liked to “blow up” cats, and some called him “the bomber,” Cooper recalled.

As an undergrad at Loyola University, the young man’s penchant for explosive materials earned him a reputation. When there was a large explosion in the dorms, eyes turned toward Betkowski.

The depression and mental health issues he struggled with for most of his life seemed to deepen after falling off a fence at a pool in Austin, Texas, in 1974, which left him with a traumatic brain injury.

When his professional career took him to Jacksonville in 1975, his coworkers at a flavors and fragrances company described him as having “bizarre” behavior. They overheard him talking about “the perfect crime” and on a separate occasion, Betkowski made a comment about how cyanide was a “less messy” option for taking one’s life.

Betkowski temporarily stepped away from the role in 1978 and returned to California for a couple months to receive psychiatric treatment at the then-UCLA Neuropsychiatric Institute. His supervisor told “Untold Mysteries” the treatment did little to help, and his employment was severed shortly after.

Writings from around that time, Cooper said, appear to show Betkowski was resistant to taking prescribed medications for his mental health issues. He “sought to find other ways of self-healing,” including alcohol and opiates, and expressed the belief that violence could bring on feelings of euphoria to help manage depression and schizophrenia.

Betkowski traded the sun-drenched, seaside Jacksonville for the dusty desert and mountain canyons of southern New Mexico along the US-Mexico border. For nearly three years, he worked on a NASA-related project at the White Sands Test Facility.

The year 1982 marked “the beginning of the end” for Betkowski, Cooper said, noting a string of tragedies, including the loss of his parents and marriage, leading up to his firing.

He was terminated following a disturbance at a Las Cruces pharmacy where Betkowski attempted to obtain some kind of capsules after which someone found he had been taking home unauthorized materials from his lab, conducting experiments in his home garden.

Not long after, Betkowski left Las Cruces, Cooper believes. He sold his car more than 800 miles away, near the Mexican border in Brownsville, Texas, before vanishing. He was found dead that December in Boise.

So many themes related to the Tylenol poisonings seemed to emerge as Cooper investigated Betkowski’s life, but no direct evidence materialized to link him to the crime or place him in Chicago during the time of the poisonings.

During the time Betkowski lived in New Mexico, police in Las Cruces reported an unsolved cyanide poisoning, in which the victim had capsulized medication, Cooper said. Testing was never done on that medication and was never determined how cyanide entered the victim’s body, but cyanide-related deaths in the US are rare enough that the Ada County Sheriff’s Office took interest.

Then there were the possessions investigators found in Betkowski’s old desk in Los Angeles: among old photos and letters were a map of Chicago and a small homemade bottle of sodium cyanide, which is distinct from the potassium cyanide used in the Tylenol murders.

Cooper next enlisted the help of Dr. Park Dietz, a forensic expert who had contributed to the Tylenol poisonings investigation in 1982, to review his investigation. Dietz, who says he believes Cooper solved the Tylenol poisonings, went on to share the findings with several expert groups, including forensic psychologists, some of whom believe they were on to something.

“Overwhelmingly they regarded him as a viable suspect. A few were convinced that he was the killer,” Dietz said at a news conference last month.

In the weeks since Idaho law enforcement made their findings public, no new suspects have been announced in the Tylenol poisonings. The Chicago and Arlington Heights Police Departments told CNN they have been in touch with the Ada County Sheriff’s Office about their findings. The Chicago FBI office, which remains the lead on the case, said the investigation is ongoing.

Betkowski’s brother, who gave the DNA sample, died in 2021. CNN could not identify other relatives or reach the brother’s estate. A search of records in the places where Betkowski was known to have lived found no criminal history.

While the answer to the puzzling case of the “Unknown Wanderer” was revealed to the world in Idaho, more than 1,350 miles away, Kasia Janus was in the midst of a particularly challenging September.

“There’s just a heaviness in my soul,” said Janus, who was 4 years old when her father, aunt and uncle died within the span of a day in September of 1982.

Adam Janus, Stanley Janus and Theresa Tarasewicz Janus were three of the seven victims who died after taking the cyanide-laced Tylenol pills, in the high-profile mystery that left consumers around America holding their breath, wary of a faceless perpetrator who could be placing poison in everyday products. Like grief itself, Janus’ Septembers have long been up and down.

This year was no exception. Janus faced the month as an empty-nester, with her son away at college as she braced for another frenzied look back at her family’s tragedy in the media.

As a child, Janus tried to make it through school everyday, and her family hoped she was too young to understand or remember the pain of losing her relatives.

“But the thing is I do,” Janus said. “I think people forget that kids are smart. They know and they feel just as much as adults – or even more.”In a sea of students, Janus would let out a sigh of relief whenever she saw another member of Rainbows for all Children, a program her mother enrolled her at aimed at helping children who needed somewhere to belong.

Some of the students, like Janus, had experienced the death of a family member. Others were dealing divorce, custody issues or other difficult life events. They had each other’s backs. She wasn’t alone.

As Janus grew, so did America’s fascination with serial killers. While the true crime industry has reexamined and sometimes helped solve cold cases, critics say that a healthy fear of danger has curdled into a morbid fascination with serial killers – the business of which has proven to be quite lucrative. Serial killer parties encourage true crime fanatics to gather in person – often with themed costumes, snacks and drinks winking at the tragedies they’re examining.

The sometimes-flippant enthusiasm with which people devour people’s real stories of loss can sting, Janus said.

That enthusiasm picks up with each potential development in a cold case. For a time, investigators in the Tylenol murder case suspected James Lewis, a Massachusetts man who served time for extortion after sending Johnson & Johnson a letter in 1982 claiming he would stop the killings in exchange for $1 million. Lewis, who died in 2023, later denied being responsible for the poisonings. At one point, authorities also looked at Ted Kaczynski, the Unabomber, who also denied any connection with the poisonings. Janus prefers to keep the conversation focused on the memory of those who were lost to the crime.

Her father, Adam Janus, who was only 27 when he died, had a sense of wisdom and ambition far beyond his years. He was the heart of the family, and had a way of bringing people together – friends, family, coworkers – he was always willing to lend a hand.

“I’ve always wished I had a chance to know him longer and to learn more from him,” Kasia Janus said. “It would have been amazing to see him in action.”Janus’ uncle and aunt had a way of making people feel welcomed and seen, she said. She still remembers how they embraced her in the moments after her father’s death – before they, too, took the Tylenol that poisoned him.

Her family and her community, the one that embraced her through her heartbreak and loss, are her focus now. As an adult, she is a board member for Rainbows for all Children and has started training to work directly with the children in her Wisconsin neighborhood. “It’s the light at the end of the tunnel for me,” Janus said.