What began as an apparent burglary in Bethesda became a cold-case pursuit that crossed the U.S.-Mexico border and returned to court years later.
ROCKVILLE, Md. — The 25-year prison sentence handed down to Jorge Rueda Landeros this month capped a homicide case in which Montgomery County detectives said DNA evidence, a border swab and a fugitive search tied him to the 2010 killing of professor Sue Ann Marcum.
The case matters not only because it ended with a conviction after more than 15 years, but because it shows how a murder investigation can hinge on one forensic link that takes years to turn into an arrest. Marcum, an American University accounting professor, was found dead in Bethesda in October 2010. Police said the scene first looked like a break-in. What followed was a reworking of that first impression: detectives said the burglary had been staged, the victim knew her killer and the key evidence was genetic material that would eventually follow the suspect into Mexico and back into a Maryland courtroom.
When officers found Marcum inside her home on Oct. 25, 2010, the physical scene sent mixed signals. There were signs of forced entry through a rear window and missing valuables, details that can point police toward a burglary gone violent. But homicide detectives later said the facts did not hold together that way. The medical examiner ruled the death a homicide caused by blunt force trauma and asphyxiation, a level of violence that investigators said fit a more personal crime. Detectives recovered DNA from someone other than Marcum and kept working backward through her recent life. Her emails and relationships became part of the map. Prosecutors later said she had become involved personally and financially with Landeros, a Spanish and yoga teacher. That shift in focus changed the meaning of the scene itself: what first looked random became, in the prosecution’s telling, an effort to disguise a targeted killing.
The forensic turn came in stages rather than all at once. Detectives learned that Landeros had crossed the U.S. border from Mexico just days before the killing and that he moved back and forth between the two countries. During one of those border crossings, agents obtained a cheek swab. The sample would matter later, after investigators compared it with DNA collected from Marcum’s home. Police said that in April 2011 the crime scene evidence identified Landeros as a suspect. An arrest warrant followed. That was a major step, but not a complete solution. By then, officials said, he had left the United States. The investigation moved from proving who might have killed Marcum to finding a man who was no longer in easy reach of Maryland authorities. The passage of time did not erase the DNA evidence, but it slowed everything else around it: interviews, extradition, charging decisions and the eventual trial calendar.
The pursuit then became international. Montgomery County officials said detectives determined that Landeros had fled to Mexico, and later reporting on the case said he assumed a new identity while away. County authorities said he was taken into custody in December 2022 through coordination involving U.S. and Mexican agencies, and officials announced in July 2023 that he had been extradited to Montgomery County. That return did not end the factual disputes inside the case. During the 2025 trial, defense lawyers argued that Landeros’ DNA in Marcum’s home was not surprising because of their prior relationship. Prosecutors answered that the totality of the evidence mattered: the victim’s financial conflict with him, the staged scene, his travel pattern and his disappearance after the killing. After an eight-day trial, a jury convicted him on Oct. 30, 2025, of second-degree murder rather than first-degree murder.
The sentencing on March 3, 2026, turned the case from an evidence story into a human one again. Marcum’s brother, Alan Marcum, told reporters that the week of trial had overlapped with the 15th anniversary of his sister’s death and that the day before sentencing had been her birthday. He thanked police, prosecutors, jurors and the judge for pushing the case to completion. Friends described Marcum not as a name in a cold-case file but as a teacher who brought imagination into an accounting classroom. A friend, Larry March, said she had recently tried to rebuild her life before she was killed. American University’s memorial page and scholarship fund keep her place on campus visible years after her death. The sentence did not change how long the case lasted, but it gave the forensic record a final legal outcome.
The evidence trail in the Marcum case now ends where it spent years trying to arrive: a sentence in Montgomery County Circuit Court. The next formal marker is whatever appellate or post-conviction steps may follow, but the central question that began at a Bethesda crime scene has now been answered by a Maryland jury and judge.
Author note: Last updated March 31, 2026.