A reward of £10,000 is being offered to help catch two burglars who threatened an elderly couple with knives.
Two men wearing khaki uniforms forced their way into the couple's home in Shooters Hill, southeast London.
Police say the men knocked on the front door of the property at around 5.30pm on 1 July and pushed their way inside when the victims opened the door.
One of the victims, a man in his 70s, suffered minor injuries but did not need hospital treatment.
The burglars stole credit and debit cards and £700 in cash, Scotland Yard said.
Detective Constable Andrew Payne said he believed the burglars may have "specifically targeted" the property in Bushmoor Crescent.
"There are people in the community that will have information about the motive and know those involved," he said.
"An elderly couple in their 70s have been left shaken by the ordeal, so any information provided, no matter how small could assist us with our investigation. We will treat all information in the strictest confidence."
One of the suspects is described as black, in his early 30s, approximately 6ft tall, of stocky build, with short dreadlocks and he spoke with an African accent.
The second man is also described as black, in his early 30s, approximately 6ft 2ins tall, of medium build, with short cropped black hair. He also spoke with an African accent.
E-fit pictures of the suspects have been released and a reward has been offered for information which leads to the arrest and prosecution of those responsible.
Anyone with information should call police on 020 8284 9449 or Crimestoppers anonymously on 0800 555 111.