A jury heard how a Wearside drug dealing gang was tracked withdrawing thousands of pounds from a bank before making trips south to buy drugs.
Nine people, including a detective constable, are alleged to have been involved in the conspiracy to bring cocaine to the streets of Sunderland.
Telecommunications analyst Darren Irving told Teesside Crown Court he had linked a number of mobile phones to the gang, and tracked their movements using cell site analysis.
“A picture emerged which is indicative of couriering,” said Mr Irving.
The court heard Asa Dobbing was the only signatory to a bank account belonging to his Aspect Garage business in Seaham.
On December 18, 2013, £10,000 was withdrawn from the account at the NatWest bank in Fawcett Street, Sunderland.
“A mobile phone linked to defendant Kevin Dudley was sited nearby,” said Nick Dry, prosecuting. “The phone was tracked to a hotel in Hitchin, Hertfordshire, before returning the next day.
“The same thing happened again on January 7 after £7,000 had been withdrawn, again on January 9 after £10,150 had been withdrawn, and again on January 10 after £3,500 had been withdrawn.
“We say these findings are consistent with courier trips to the south to buy drugs.”
Intelligence officer Detective Constable Gary Christie, who was based at Boldon police station, is alleged to have used his access to investigative information to assist the gang.
The court heard from another intelligence officer, Detective Constable Vanessa Tilley, who was based at a special firearms intelligence unit at Northumbria Police headquarters in Ponteland.
Det Con Tilley told the court she spoke to Christie on the telephone who told him he had some intelligence to pass on, but seemed reluctant to say what it was.
“I was a bit confused by the call,” said Det Con Tilley. “I never got to the bottom of it.
“I was uncomfortable with the conversation, so I spoke to my sergeant about it.”
The jury was told they will hear evidence from the sergeant later in the trial.
* The following all deny conspiracy to supply class A drugs between August 2012 and April 2014.
Asa Dobbing, 36, of Ryhope Grange Court, Ryhope, Aidan Dobbing, 31, of Ravelstone Close, Doxford Park, Sunderland, Simon Loomes, 41, of Duke’s Valley, Gerrards Cross, Buckinghamshire.
Kevin Dudley, 20, of Hadrian Park, Jarrow, Victoria Carter, 25, of St Oswyn Street, South Shields, April Hunter, 20, of Union Quay, North Shields, Christopher Catchpole, 49, of Church Walk Thornley.
Gary Christie, 41, of Silksworth Lane, Sunderland, denies the drugs conspiracy charge, and he denies misconduct in public office.
Asa Dobbing denies aiding and abetting a person to commit misconduct in public office.
The following admitted conspiracy to supply class A drugs at an earlier hearing.
Jamie Malloy, 27, of Swan Street, Monkwearmouth, and Leanne Marriner, 33, of Avonmouth Road, Farringdon, both Sunderland.
The trial is expected to last up to four weeks.
* The trial continues.