Details of Disappearance Lisa was last seen in Potomac, Maryland on July 14, 1988. She has never been heard from again. Her common-law husband, Gregory Mung-Sen Tu, says he put her on a plane to San Francisco, California at 5:00 p.m. that day. He said she was going to visit a sick friend. She never arrived in that city, however.
Authorities discovered that a plane ticket to San Francisco had been purchased in Lisa's name, but other passengers on the plane reported her seat was empty. The sick friend she was supposedly visiting was in fact in good health and had not heard from Lisa in months. In addition, although one of Lisa's suitcases and some of her favorite dresses were gone, she left behind other items she normally took with her when she traveled.
Two days after Lisa vanished, Gregory paid a garbage collector to get rid of a loveseat in their residence. It was in good condition and Lisa often slept on it. It was never found and is believed to have been pulverized at a landfill.
When investigators searched the Tu home, they found a meat cleaver, twine and plastic wrap in his Lincoln Town Car. There was blood on the dashboard of the family car, and blood was also found in the basement near where the loveseat had been. The area had been cleaned and most of the blood was not visible, but when investigators sprayed Luminol, a chemical used to detect blood traces, they discovered a significant amount of blood in the basement and a blood trail to the bathroom and up the stairs. DNA testing, which was a new technology at the time, proved the blood was from Lisa.
Lisa and Gregory had been living together for ten years prior to her disappearance and referred to each other as husband and wife, but they were not legally married, and Lisa was also having an illicit relationship with another man. Gregory was a suspect in Lisa's case since shortly after she disappeared.
Lisa was financially secure, but Gregory was having financial difficulties. He withdrew $44,000 from Lisa's son's college fund without her permission five days before she vanished and deposited the money in his own account. Investigators believe Lisa found out and had an argument with him about it.
Although Gregory says he had a good relationship with Lisa at the time of her disappearance, others maintain the couple argued frequently, usually about money, and Lisa was considering kicking him out. The couple's house, which was worth $250,000, was in Lisa's name only. The state of Maryland does not recognize common-law marriages, so if Lisa decided to end her relationship with Gregory, he would have had no rights to her property.
After Lisa's teenage son reported her missing, authorities questioned Gregory and he agreed to take a polygraph test in two days. The next day he left the area without notifying anyone, before he could take the test. He was later traced to Las Vegas, Nevada.
In September 1988, Gregory was arrested in Las Vegas and charged with first-degree murder in Lisa's case. He was convicted the following year, but the conviction was overturned. He was retried and convicted of second-degree murder in 1992, six years after Lisa vanished. Prosecutors believe he shot Lisa to death inside their home. Gregory owned a Browning .380 pistol which vanished from the home around the same time Lisa did.
Gregory is still incarcerated. Lisa's remains have never been located.
- Montgomery County Police Department
Updated 3 times since October 12, 2004. Last updated October 7, 2020; height and weight added, distinguishing characteristics updated.