Jorge Landeros has taken to taunting the police from his new home in Mexico. The man accused of killing American University accounting professor Sue Marcum sent an e-mail to an El Paso detective recently to say that he wouldn’t come to the United States to answer questions.

“Of course you are cordially invited to cross the same bridge, in the opposite direction, and meet me at Sanborn’s, a great cafe and restaurant here in Juarez, and we can talk shop all you want,” Landeros wrote. “It’s best if you come on a Sunday. We can have brunch. It will of course be my treat. Yours, Jorge.”

It was that same brash charisma that drew Marcum to Landeros in the first place and now has marked him as a fugitive in an international murder case.

The death last fall of the popular teacher shocked the quiet Northwest campus and the Bethesda neighborhood where Marcum lived. It must have been a burglary gone bad, her friends and police said at the time, especially when a District teenager was arrested driving Marcum’s missing sport-utility vehicle.

But then detectives learned more about Landeros, the egocentric charmer 12 years younger than Marcum. The two met about six years ago when she enrolled in a Spanish class he taught in Dupont Circle. He wrote poetry, studied yoga, day-traded stocks. Together, they practiced meditation before dawn, read books, went to concerts.

In a series of interviews by telephone from Mexico, Landeros denied that he killed Marcum but volunteered that he was the sole beneficiary of her half-million-dollar life insurance policy and that they invested money together. He described his relationship with Marcum as special, idiosyncratic and deep. For a brief period, he said, it turned into something more.

“We climbed that wall of romantic love at some point, but there was nothing behind the wall,” he said. “There was nothing that could progress in that direction.”

He said he was not in the United States in late October, when Marcum, 52, was slain. He answers e-mails from detectives, sometimes correcting their grammar, but declines to cross the border.

“I had nothing to do with the murder of Sue Marcum. That was not me,” Landeros said. He added: “They want me to just turn myself in, like some silly scapegoat.”

Police will not discuss specifics of their case against Landeros, other than to confirm they were able to obtain a DNA sample from him this year when he traveled to Texas.

They later obtained a warrant charging him with first-degree murder. Marcum’s body was found in the lower level of her home Oct. 25. An autopsy showed blunt force trauma and asphyxiation.

Montgomery County police have sought help from Interpol and authorities in Mexico to locate Landeros and bring him to the United States, said Officer Janelle Smith, a police spokeswoman.

“There is a process to be followed. That process takes time,” Smith said.

To Marcum’s friends, Landeros’s boasting and the flippancy with which he describes the case is infuriating.

“If he’s so innocent, why is he staying in Mexico?” said fellow accountant Don Williamson, who, like others, thinks Landeros took advantage of a woman who had hundreds of friends but lived alone. “She was fascinated by that man. She was a loving, beautiful, vulnerable woman.”

Born in Ciudad Juarez, Landeros moved to Ohio when he was 13. He read philosophy and was inspired by a teacher who insisted students learn lots of new words. “To the eternal discomfort of my close friends, I have a large vocabulary,” he said.

He said he studied at colleges, traveled in Europe and Latin America and arrived in the Washington area about 10 years ago.

He wore expensive suits as a stockbroker and jumped among six jobs over three years in and around the District, including at Morgan Stanley and American Express Financial Advisors, according to records kept by the Financial Industry Regulatory Authority.

By 2005, he said, even as he was still trading stocks on his own, he was making changes in his life.

He studied at a yoga center in New York. He holed himself up in rooms for days on end while sustaining himself on water, yoga and meditation. He also taught Spanish classes.

Marcum, who was beloved by her students and friends for her bubbly personality and ability to make accounting fun, joined one of those classes.

She was known for that personality throughout her career. In 1988, while interviewing for a tax management position at Ringling Bros. and Barnum & Bailey Circus, she didn’t hide her eagerness.

“I’d do cartwheels across your office, but I’m wearing a skirt,” the barely 5-foot-tall prospect told company comptroller Andrew Zino, who hired her on the spot.

It was a complicated job: The company ran circus and ice shows throughout the country and overseas, prompting all manner of state, federal and international tax issues. Marcum led the tax department from a number-crunching unit to one that had real influence on the direction of the company, said Laurie Guardia, then the finance director.

“Impeccably organized,” is how Guardia put it in a letter of recommendation to American University, where Marcum landed a teaching position.

In the classroom, with her brightly colored scarves and funky eyewear, she wove circus taxation stories into lectures.

Students who’d signed up for just one accounting class suddenly made it their major. She mentored them while working with the accounting club.

Outside of work, Marcum co-founded and helped raise money for an inner-city District program to help parents prepare their pre-schoolers for the classroom. She threw herself themed birthday parties every year for her ever-expanding circle of friends.

“Sue was passionate about everything she did,” said Beverly Myers, a close friend.

That included traveling to South America and learning Spanish. And by 2005, she was telling Myers and others about her teacher. “It was his charisma that got her,” Myers said.

Marcum’s friends found Landeros to be a mystery — the person she always talked about but rarely brought around.

One exception: Marcum’s 49th birthday party, when she told guests to wear comfortable clothing if they wanted to try Thai yoga, a practice in which the instructor helps participants bend into certain positions. Landeros was an instructor.

Williamson met Landeros in a different setting when Marcum brought him to Williamson’s office for advice.

The IRS had filed a $3.3 million tax lien against Landeros because he didn’t file tax returns on proceeds from stock sales, according to court records and Williamson. The matter was settled with the IRS for far less, Williamson said, but Landeros’s attitude rubbed him the wrong way. He later called Marcum to advise her to quit hanging out with him.

Landeros said the IRS had only been accounting for his stock sales, not his stock purchases, and things eventually were resolved easily with the government.

Landeros said that as they grew closer, he made Marcum the beneficiary of his life insurance policy, and she made him the beneficiary of hers. “We always talked about what would happen when we got older,” he said. “We would help each other, I guess . . . We took it out for that reason.”

But Landeros said he worries that the policy has drawn police attention to him. He said that State Farm contacted him and told him nothing had changed.

“I’m wishing now that she had modified hers,” he said. “Sadly, she did not change her mind in time.”

Landeros has not received the insurance payment. In a March 4 letter to Landeros, State Farm wrote that “due to the circumstances of death, we are gathering additional information which may affect benefits.”

Landeros, who police say holds dual citizenship in Mexico and the United States, left the Washington region for Juarez in 2008, telling friends and family he wanted to teach yoga in his violence-torn home town. Marcum also told friends that Landeros thought he could help the area. “She believed there was good in him,” said Cathy Vincent-Smith.

“Truly, Juarez is violent, very violent, too violent,” Landeros wrote in a 2010 book about yoga in the city. “We have an international reputation. Only a bourgeois idiot would say that is not cause for pride: In the liquid world of postmodernity, it will not be the sheep that survive.”

In Washington, Marcum poured herself into work and training for a 5K road race. Friends said she seemed happy. Over lunch at the Bethesda Crab House on July 4, 2010, her friend Vincent-Smith asked Marcum about Landeros. Marcum said she feared for his safety in Juarez.

By the morning of Oct. 25, the person who killed Marcum had made his way inside her home along Massachusetts Avenue.

As detectives began to learn of Landeros’s relationship with Marcum, they tried to lure him across the border.

In early March, he bit and came to El Paso to meet Detective Ray Sanchez, who left with a DNA sample from the inside of Landeros’s mouth.

A short time later, Montgomery detectives obtained an arrest warrant charging him with first-degree murder.

But by then, he was back in Juarez. Sanchez sent Landeros an e-mail, asking whether he wanted to look at photographs to help in the case, according to e-mails supplied by Landeros.

“As far as the pictures, sure I can help,” Landeros wrote. “Perhaps the Maryland authorities have heard of JPG formats, through which they can forward electronically those and any other pictures they would like for me to see.”

In an interview Wednesday, Landeros acknowledged he was inside Marcum’s house as recently as September, when he’d returned to the area to visit his mother, who lives in Northern Virginia.

Landeros said he and Marcum talked, went for a walk, ate and watched TV. He said his fingerprints and DNA would be in the house from that and previous visits.

“I understand what they see from their end,” he said. “They’ll find me all over the place if they look hard enough. . . . I drank wine from glasses there. I drank water from the glasses there. I’ve eaten with the forks there. I slept in that bed and the sofa.”

“It doesn’t look good,” Landeros said. “That’s why I’m here in Mexico.”

Staff researcher Jennifer Jenkins contributed to this report.