Robyn Mercer, 50, was found dead in West Molesey, Surrey, on March 14.
No-one has been charged with the killing.
Today specialist teams began searching Littleheath Pond in Oxshott, as police pledged to “relentlessly” pursue the mother-of-two”s murderers.
A post-mortem examination found that the keen rower died from multiple blows to the head.
Detective Chief Inspector Paul Rymarz said: “Today”s search is being carried out to establish if there is any new evidence which could help to identify those who committed the brutal attack on Robyn.
“We will continue to pursue all potential leads and will relentlessly carry on until the offender/s are behind bars.”
Ms Mercer, a silver specialist, worked at family firm JH Bourdon-Smith in Mayfair, west London.
Currently five people are on bail in connection with the investigation.
Two men, both aged 26 and from West Molesey, were held on suspicion of conspiracy to burgle and murder and are due to answer bail on December 16.
One is also suspected of conspiracy to pervert the course of justice.
Two women, aged 20 and 45 and from Oxshott, were arrested on suspicion of conspiracy to pervert the course of justice and have been bailed until December 16.
A 53-year-old man, from West Molesey, was held on suspicion of fraud by false representation and is due to answer bail on November 21.