When deliveryman Marco Jap took a parcel to lawyer Rengarajoo Rengasamy Balasamy's office on the morning of Aug 10, 2011, he saw the latter's former client, Govindasamy Nallaiah, alone in the room holding a thick bicycle chain.
Govindasamy told him that none of the firm's employees was in and to wait outside for 10 minutes.
But shortly after he went outside, he heard loud "thuds", which sounded like a hammer hitting the floor. He also felt vibrations and smelled something burning. Then he heard a woman screaming and saw smoke coming from the office.
Yesterday, Mr Jap took the stand as a key prosecution witness on the second day of a murder trial in the High Court.
Govindasamy, 70, a former client of Mr Rengarajoo, stands accused of killing the latter's wife, Madam Low Foong Meng, 56. Her charred body was found inside the office of her husband's firm, on the sixth floor of the Afro Asia Building.
The prosecution's case is that Govindasamy, angered over a legal fee dispute lasting almost a decade, took a bicycle chain and padlock from his bag and hit Madam Low on the head until she collapsed.
Shortly after, Mr Jap came by and interrupted the supposed murder.
After Mr Jap left the office, Govindasamy allegedly used a lighter to set alight some files on a table, then watched the fire spread before leaving Madam Low unconscious inside the burning unit.
Mr Jap yesterday testified that he thought Govindasamy was doing construction or renovation work, and that an accident had occurred. He did not open the office door when he saw smoke as he was afraid that the unit might explode.
Mr Jap reported the matter to a security guard on the ground floor.
Later, he saw Govindasamy "walking briskly" and "in a hurry".
A forensic pathologist who performed an autopsy on Madam Low testified that he found three cuts on her body, which were likely caused by "a sharp, cutting instrument", such as a knife or a cleaver.
She also had five fractures to her skull, and the damage caused to her brain possibly rendered her unconscious, said Associate Professor Gilbert Lau. The senior consultant forensic pathologist with the Health Sciences Authority found the cause of Madam Low's death to be from the inhalation of fire fumes and extensive severe burns.
Prof Lau told the court that two of the three cuts he found were "defensive injuries". One almost sliced off the tip of her left middle finger, while another was on her elbow.
Madam Low's head injuries, meanwhile, caused some bleeding in the brain, but would not have been serious enough to kill her.
The"copious amounts of soot" in her airways and lungs, and "lethal" level of carbon monoxide in her blood, also meant she must have been alive at the time of the fire.
Prof Lau will be cross-examined by Govindasamy's lawyers later.
The trial continues today, with Govindasamy's four children and a family maid expected to take the stand. He faces the death penalty or life imprisonment if convicted.