An iPhone, an iPad and "unknown device" listed on Ms Brooks' home router were not recovered in searches on the former News International chief executive's office and addresses in London and Oxfordshire, Detective Constable Philip Stead told the court.
News International also provided details of three BlackBerry phones, an HTC phone, two Apple iPhones and an Apple iPad thought to be linked to Ms Brooks.
In all, the court heard there were up to 10 devices in use up until September 2011 unaccounted for by police.
However, one phone may be a duplication, another may belong to someone else and an iPad may have been lost.
It recently came to light that one of the phones linked to the Oxfordshire router has since been claimed by Sir Charles Dunstone, the Carphone Warehouse boss, Mr Stead said.
The judge, Mr Justice Saunders, quipped to the jury: "He probably has a lot of phones!"
The trial has heard previously how Ms Brooks left with just her handbag and a disabled BlackBerry phone after she resigned from her job in July 2011.
Her office was sealed off by NI staff and computer equipment was bagged by police for examination.
Police later seized computer equipment in a search of Brooks's London home while she was in custody and were handed two bags containing two laptops stashed overnight in the underground car park of the Chelsea Harbour flat.
Mrs Brooks, 44, of Churchill, Oxfordshire, denies conspiring to hack phones, conspiring to commit misconduct in a public office and conspiring to pervert the course of justice.
All seven defendants in the case deny the charges against them.
Jonathan Laidlaw, QC, defending Ms Brooks, suggested explanations for the missing devices - that they may have been broken or lost and replaced.
He said: "We will never know, will we?", to which Mr Stead replied: "No, not in relation to these devices." The trial continues.