Victims Will Henry, 31, and Brian McIntosh, 29, were discovered in a Range Rover after police were called to a car park at the Albion Works off Moor Street, Brierley Hill , on September 30, 2020.
Mr McIntosh, driving, was shot four times at close range to the left side of his face and neck, causing "very rapid" death, prosecutors said.
Mr Henry, in the front passenger seat, was shot twice, including just behind his right ear, damaging the brain stem "which would have resulted in near instantaneous death", jurors heard.
Jonathan Houseman, 32, of no fixed address but formerly of Quarry Park Road, Stourbridge, and Richard Avery, 33, of no fixed address, both deny murder, with Avery also pleading not guilty to a separate charge of perverting the course of justice.
Jurors heard that CCTV allegedly shows Houseman getting out of the victims' Range Rover after the killings, moving a car he used to leave the murder scene and covering his face from a security camera, which was "all part of the planning and preparation for the shooting".
Afterwards, prosecutors have claimed he washed himself, handing over his clothes to Avery for disposal.
Forensic examination of two bullet casings found in the Range Rover showed a partial DNA profile belonging to Avery, jurors heard.
Avery's partner, 33-year-old Francesca Scott, of Lower Valley Road, Brierley Hill, is also on trial accused of perverting the course of justice after allegedly disposing of clothing or other items between September 30 and October 2, 2020.
Jurors also heard she bought a phone and disposable sim card, giving it to Avery who then used it to contact Houseman after the shooting, who by then had driven to Lancashire with his family to stay in a caravan.
Opening the case at Birmingham Crown Court on Thursday, Michael Burrows QC said: "On Wednesday September 30 last year, Brian McIntosh and Will Henry were both shot and killed while in a Range Rover at the Albion Works industrial estate.
"The prosecution say the man who shot them was Jonathan Houseman, and that he was the only other man in the car with them.
"CCTV at the scene captured the moments of the shooting; it shows the car being manoeuvred about to complete a three-point turn, it shows the puffs of smoke from the shots and the car then rolling slowly forward into some fencing.
"It then shows Jonathan Houseman getting out the rear of the car. Nobody else got out."
Mr Burrows added that Houseman was seen on CCTV, using a gap in the yard's fencing, to get to a silver Vauxhall Astra which he had earlier parked nearby.
Houseman then drove to Avery's car wash business; the H20, in nearby Merry Hill where Avery "helped him wash and change his clothes", the court was told.
Avery rang Scott, who arrived "to collect a bag containing Jonathan Houseman's clothing and other items, no doubt linking him to the shooting", the jury heard.
Scott took the bag home and "bought an incinerator to burn the clothing or other items, in it", said Mr Burrows.
The Crown's QC added that the defendants deny any wrongdoing.
"As I understand it, Jonathan Houseman accepts he was in the car, but says there was another man in the car and it was the other man who shot Brian McIntosh and Will Henry," said Mr Burrows.
"Richard Avery says he wasn't involved in the shooting at all.
"He accepts he helped Jonathan Houseman afterwards but said he did so only because he was threatened by someone else."
Ms Scott has claimed she "didn't know of any criminal act, so didn't intend to pervert the course of justice".
Mr Burrows said Houseman had previous dealings with the victims, who "worked together in waste clearance".
Houseman, who also worked in waste clearance, had a site in the Mucklow Hill area of Halesowen containing about "1,000 tons of waste", which he hired Mr McIntosh and Mr Henry to clear "for a fee".
Mr Burrows said: "However, he didn't pay them for the work they did," adding: "At one point in 2019, Jonathan Houseman owed Brian McIntosh and Will Henry around £200,000."
He said Houseman "paid them some money" but told jurors they would hear from another business associate, who said the two victims became "increasingly frustrated" when Houseman failed to make payments.
The associate would claim the victims "could be intimidating and were capable of causing problems".
The jury were read a text message sent on September 25 from Mr Henry to Houseman which read: "Need to fix up Jon - out of order what you are doing."
During the Covid-19 pandemic, Houseman purchased four companies "which fitted the criteria of the Government bounce-back loan - each loan could raise £50,000" and it was "understood Mr Houseman would use the loans to clear his debts".
Houseman's mother, who had lent him £175,000, told police her son was "under stress" before the killings, telling her he "needed to pay people off or they would kill him".
Jurors also heard a claim that Houseman owed Avery £100,000 and had signed over a Porsche 911, in part to cover that debt.
Mr Burrows said: "You may consider that background provides Jonathan Houseman with a clear motive for these murders.
"No doubt he hoped killing [the victims] would relieve him of the burden of debt he owed them."
The trial continues.