Police revealed that Sana's ex-husband had bought two crossbows months prior to the attack and carried out surveillance on her house.
A man has been found guilty of murdering his pregnant ex-wife with a crossbow as she fled up the stairs, say police.
Sana Muhammad, a 35-year-old mother-of-five was killed on November 12, 2018, at her home in east London.
She was eight-months pregnant at the time.
The conviction comes ahead of the International Day for the Elimination of Violence against Women on Monday, November 25.
Ramanodge Unmathallegadoo, 51, had hidden in the shed at the end of Sana's garden armed with two crossbows.
Unmathallegadoo was found by Sana's husband, Imtiaz, who he then chased into the house.
Imtiaz told Sana to flee up the stairs but Unmathallegadoo shot her with a crossbow before she could get to the landing.
"The arrow, which measured 18 inches, entered Sana’s body in her hip and travelled up through her body. By extreme fortune, it missed the unborn baby," the Metropolitan Police said in a statement.
Unmathallegadoo, who shared children with Muhammad, was disarmed by his son at the scene.
Muhammad was transported to hospital where her baby was delivered by caesarian but had to be revived because he was not initially breathing. She died as the injuries caused to her internal organs, including her stomach, liver and heart, led to her suffering a heart attack.
The police's investigation revealed that Unmathallegadoo had been planning the attack for months. He had bought the first crossbow online for £1,000 in March and the second one in May. He also bought archery arrows, broadheads and bolts from different suppliers via eBay in what prosecution argued was a bid to ensure his purchases didn't draw any attention.
Detectives also found a rucksack in the shed which contained a pair of scissors, a roll of duct tape and a chart marking the dates and times of the movements of the occupants of the house. In October, he had asked his daughter whether the shed was locked.
Unmathallegadoo, who refused to answer any questions when interviewed by police, told the trial that he had been aiming the crossbow at the bannister and had not meant to kill his ex-wife.
He will be sentenced on November 29.
Detective Sergeant Amjad Sharif, who led the investigation, said Unmathallegadoo killed his ex-wife in "cold-blood."
"The circumstances and detail of the case are harrowing and I would like to pay tribute to the strength and dignity of Sana’s friends and family, some of who have given evidence during the trial. Unmathallegadoo’s actions on the 12 November 2018 have left six children, including a newborn baby, without a mother and a husband mourning his wife," the official added.
Imtiaz Muhammad said Sana had been a "very outgoing and bubbly" person.
"She was my soul mate, my best friend, my wife, my companion and my everything and I love her dearly.
"Ram must have been very jealous of the life Sana and I had and that we were living a happy life. Sana was feeling scared since Ram had started seeing the kids. She would always say ‘Ram does not forgive and forget’ he likes to create trouble no matter if he loses everything," he went on.
According to the United Nations, 58% of the 87,000 women murdered in 2017 were killed by intimate partners or family members. More than a third of women intentionally killed were murdered y a former or current intimate partner.