Guen Garlejo Aguilar was born on April 19, 1976, in Tagudin, Ilocos Sur, Philippines. She moved to Singapore in 2001 to work as a domestic helper. During her employment, she became close friends with fellow Filipino maid Jane Parangan La Puebla, whom she met in March 2005. Their friendship deepened over time, with both women considering each other as sisters. 

On September 7, 2005, Jane visited Guen at her employer's residence in Serangoon, Singapore. The meeting was intended to discuss a S$2,000 debt that Jane owed Guen. Half of this amount was from Guen's personal savings, while the other half was borrowed from another maid, with Guen responsible for repaying it at a 20% interest rate. During their conversation, Guen suggested that Jane sell her video and digital cameras to settle the debt. This suggestion led to a heated argument, escalating into a physical altercation where Guen bit Jane's arm. In the struggle, Guen smothered Jane with a pillow until she became unconscious. When Jane regained consciousness, Guen strangled her until she died. ​

After the murder, Guen concealed Jane's body in her room for two days. On September 9, she purchased a chopper, an axe, gloves, and garbage bags from Mustafa Shopping Centre. She then dismembered Jane's body, placing the parts into two separate bags. One bag was left near Orchard MRT station, and the other at MacRitchie Reservoir. The remains were discovered later that day, leading to Guen's arrest in the early hours of September 10, 2005. ​

Initially charged with murder, Guen's charge was later reduced to culpable homicide not amounting to murder, considering her mental state and diagnosis of depression at the time of the offense. She pleaded guilty and was sentenced to ten years' imprisonment on May 29, 2006.