Earlier the court heard from Ewan Fraser, a watch commander at Helensburgh fire station.
Harkins, 45, formerly of West Princes Street, Helensburgh, was given six months to pay the sum.
Originally from Helensburgh, Dunbartonshire, Richards now lives in Cowes on the Isle of Wight.
Her husband had been out at his local pub, the Ashton, in Helensburgh that night, she said.
Scott Snowden, 50, and Robert Jennings, 37, are accused of setting fire to their home in Helensburgh.
Thomas Sharkey, 21, and eight-year-old Bridget died in the blaze at their home in Helensburgh in July 2011.
Harkins' assets included cash seized, money in bank accounts and his share of equity in a property in Helensburgh.
Bridget Sharkey and her 21-year-old brother Thomas died following a deliberate fire at their home in Scott Court, Helensburgh on 24 July.
The Trident missile system, Britain's nuclear deterrent, is carried by submarines based at the Faslane naval base on the Clyde, near Helensburgh.
The Marine Conservation Society also found high levels of pollution at East Bay in Helensburgh, Footabrough in Shetland, and Edinburgh's Cramond Beach.
Helen Steven, 28, from Helensburgh, and Lynn McCulloch, from Kirkintilloch, near Glasgow.
The Helensburgh teenager died, along with Georgia Rowe, who was 14 and from Hull, after they plunged from the Erskine Bridge in October 2009.
Steven Smith, from Portincaple near Helensburgh, told the BBC Scotland news website he hoped they would find officials at a different border crossing would be more helpful.
Earlier, Mr McCarthy told the court that he had been "drip-feeding" information about several fires in Helensburgh to police because he feared for his family.
Two men are to stand trial accused of murdering three members of the same family by setting fire to their home in Helensburgh, West Dunbartonshire.
Tim Hughes, Helensburgh, Scotland: My wife and I have three children and all were put outside in a big pram twice a day for their nap.
Mr Snowden denies setting the fire at Kingspoint and he and Mr Jennings deny pouring petrol through the letterbox of the the house in William Street, Helensburgh.
It is also alleged they attempted to murder Mr Sharkey's wife Angela - the children's mother - during the same blaze at the property in Scott Street, Helensburgh.
Det Con Campbell agreed that the 999 call had been made from a telephone box in Helensburgh and confirmed that it was to provide information in relation to the fire at Scott Court.
Edinburgh and Helensburgh are Scotland's least affordable areas.
Back on dry land, William went on to meet Naval families, local community groups and youth groups when he opened a refurbished room at the Drumfork Club in Helensburgh, a social club for Naval families.
BBC: NEWS | UK | Scotland | Glasgow, Lanarkshire and West | Prince joins Marines at Faslane
He told told prosecutor Alex Prentice QC that in his opinion a fire at Kingspoint, Shandon, on 5 July, 2008 and a house fire at 4 William Street, Helensburgh on 6 January, 2011 were started deliberately.
Both men have lodged special defences of incrimination and alibi, with Mr Snowden claiming he was in Mexico when the fire at the Sharkey home was allegedly started, while Mr Jennings claims he was home alone in Helensburgh.
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