How a passenger's confession helped convict her cousin of murder

Warning: This article contains distressing content

One afternoon in April, a children's nursery worker approached her manager in what she described as an hysterical state.

Gabrielle Debotte said she had something serious to tell Nicola Goddard, adding: "You're going to hate me and I'm going to lose my job."

What the 27-year-old said next proved a turning point in the investigation into the death of popular head teacher Michael Mullins, who had been struck by a car the previous day and dragged under its wheels for more than a mile.

Debotte told the astonished Goddard she not only knew who was responsible for hitting the 56-year-old as he cycled home from work, but she witnessed what happened from the passenger seat.

That night, having initially been treated as a suspect, she sat in the interview suite at Stretford Police Station and named her cousin, 35-year-old former mechanic Simon Richardson, as the driver.

Thanks in part to the evidence provided by Debotte, Richardson was found guilty of murder after a two-week trial at Manchester's Minshull Street Crown Court.

The contrasts between the lives of the killer and his victim were stark.

Less than a month before he struck the head teacher, Richardson was freed from prison.

He had served 47 days on remand awaiting sentence for stalking, harassment, threats to damage property and assaulting an emergency worker, and was freed on 26 March after being sentenced to a non-custodial community order.

In the following weeks, he was "sofa-surfing" between various addresses - including the home Debotte shared with her father in Altrincham, Greater Manchester.

In contrast, the head teacher had spent the past 17 years leading Stretford Grammar School, where he was known as a man of "unshakeable principles and a compassionate leader".

To his family, he was a beloved husband, father and grandfather, who "truly excelled" in his "role as grandad".

He was a lover of sport and remained physically fit, regularly cycling the 19 miles between the school and his home in Northwich, Cheshire.

At 17:35 BST on 20 April, he changed into his cycling clothes, put on his helmet and set off as normal.

Detectives would later be able to plot his journey via his Apple watch, which monitored his speed, location and heart rate.

Not far from the cyclist's starting point, a black Volvo XC90 was already catching the attention of other drivers as it sped "erratically" along the semi-rural roads on the outskirts of Trafford and north-east Cheshire.

It was being driven by Richardson, who had agreed to give his cousin a lift from Altrincham to a beauty salon in Lymm to pick up some weight-loss jabs.

In court, Debotte told jurors Richardson had been driving very fast and when she told him to slow down, his only response was to "smirk" and claim he was "a professional driver".

At 18:07, the car reached a junction in Warburton, Trafford, which connected Dunham Road with Paddock Lane.

According to Debotte and other witnesses, the Volvo ignored stop signs and road markings on Dunham Road as it attempted to turn left.

Debotte told the court she shouted "bike" three times, but Richardson made no attempt to slow down or brake before the Volvo smashed into the left side of the cyclist.

Witnesses saw the head teacher being thrown into the air while his bike, phone, part of his helmet and a wireless earphone were scattered across the road.

Witness Leon Dalziel-Bush, who saw the crash from his own vehicle, said the Volvo was going at such speed that "by the time I processed what had happened, it had gone".

Dalziel-Bush and others got out to help, but after searching in ditches and grass verges, they realised the cyclist was nowhere to be seen.

Richardson, who according to Debotte, stopped for a "split-second" before accelerating away, was already guilty of very serious criminal offences.

What happened over the next four minutes or so, prosecutors argued in court, made him a murderer.

The prosecution case hinged on whether it could prove Richardson was aware the cyclist was trapped and suffering increasingly appalling injuries just inches from his feet.

Phil Barnes KC, prosecuting, told the jury that many of them would know what it feels like to drive "with a flat tyre, or with wheels that are slightly out of balance or misaligned".

"Now imagine driving your car, at north of 60mph, with a fully grown human being wedged in the suspension and steering assembly of one of your wheels," he said.

Barnes had suggested it "must have been obvious" to Richardson that the 56-year-old was there, but "he carried on regardless", knowing his actions "were in all likelihood killing the man beneath his feet".

But, thanks to Debotte's workplace revelation, the case was built on much more than that simple premise.

When she gave her statement to police, she described a scene of absolute shock and panic in the car, complete with "screaming and crying".

"I had never seen anything like that in my life," she said, adding: "I still have visions of it."

She also recalled how "moaning" could clearly be heard from beneath the Volvo as it sped away and that Richardson blurted out: "He's under the car."

Detectives would be able to prove, via watch and phone data, that his car had stopped on Wet Gate Lane in Lymm a short time after the collision.

The data showed the car had remained stationary on the rural country lane for about 90 seconds, as the cyclist was still clinging to life.

Debotte's account of those moments was absolutely crucial to proving Richardson was guilty of more than causing death by dangerous driving and failing to stop.

She said as she sat "frozen" in the passenger seat, he got out, walked around the front of the vehicle and tried to pull the head teacher free.

When the first attempt failed, he returned to the driver's seat and moved the steering wheel to try and free the wheels.

Debotte said Richardson got out again and crouched down to make another attempt to pull his victim free.

After failing again, he started the engine and drove further along Wet Gate Lane.

CCTV from a nearby farm showed the car swerving from side-to-side before the cyclist was finally thrown clear on to a grass verge.

From the position he was found, prosecutors were also able to say that the car must have driven over his body when it reversed and turned back towards the main road, all but ensuring his injuries were fatal.

The court was shown distressing evidence in support of Debotte's account, including images of a sharp-angled tyre mark left in a pool of blood where the car had stopped.

The jury heard the mark could only have been made by the wheels being turned while the car was stationary.

Nobody was around when the 56-year-old was thrown from the vehicle and left to his fate, but a few minutes later, motorcylist Andrew Beasant-Roberts found him after following a trail of blood from close to the crash site just over a mile away.

Beasant-Roberts made a 999 call and tried to perform CPR, but it was too late.

Detectives later found CCTV footage which showed Richardson and Debotte at Lymm Service Station minutes later, filling the car with petrol.

The pair then finished the errand they initially set out to do and picked up Debotte's jabs from the salon in Lymm.

She was dropped off at her Altrincham home at 18:45, where she stayed until she left for work again the following morning.

After dropping her off, Richardson quickly arranged to swap the Volvo for a silver Ford Transit work van with an associate.

He returned to Debotte's house in the van with a friend and the pair came and went from the house throughout the night.

Debotte said the men had been "laughing and joking" while listening to music and drinking her father's alcohol, but Richardson also lost his temper when she asked them to leave, punching a hole in plasterwork and kicking a chair.

She said there were no direct threats, but Richards outlined an account for her to give to police if they came knocking, which she wrote down in a note-taking app on her phone.

It included instructions to say she had lent Richardson her bank card on the day before and had not seen him again until late on the day of the crash.

However, Debotte said she already "knew she was going to talk to the police" and would be telling the truth.

In court, Debotte accepted she "absolutely" could have done more to alert the police to what had happened earlier, but her decision to seek them out before anyone else knew she had been in the vehicle allowed them to treat her as a witness.

Based on her description of the van, Greater Manchester Police officers found it the following day in Failsworth.

Despite knowing he was being tailed by a trained pursuit driver, Richardson tried to flee, first speeding through narrow residential streets and then making a final futile attempt to escape on foot.

He has never given a public account of his actions on 20 April.

The court heard he declined to answer police questions and on 22 October, at the conclusion of the prosecution case, the jury were told he would not be giving evidence in his own defence.

Jaime Hamilton KC, defending, explained while questioning witnesses that Richardson denied he knew the cyclist was under the car and denied he had got out of the vehicle on Wet Gate Lane.

However, the evidence and the testimony of Debotte meant the jury were sure he was guilty of more than a serious driving offence and fully convinced he had made the conscious decision to drag a helpless and well-respected family man to a most horrific death.

Richardson is due to be sentenced on Monday.

Listen to the best of BBC Radio Manchester on Sounds and follow BBC Manchester on Facebook, X, and Instagram. You can also send story ideas via Whatsapp to 0808 100 2230.