But in many ways Pearce, 61, fitted the stereotype of the deranged but intelligent recluse who spends years trying to beat the system and devise the perfect crime.
He was motivated by money, obsession, a desire for notoriety and the satisfaction of outwitting Scotland Yard's finest while terrorising large sections of London.
As always in these cases, the unmasking of Pearce as the man behind the Mardi Gra came as a shock to neighbours and relatives.
Pearce was described as an unfriendly, reclusive man who drank heavily and quarrelled about the parking space in front of his home. He was nasty to children, had bizarre eating habits, but was considered "intelligent and frustrated".
Unemployed, at one point he worked for his younger brother, Philip, who runs an advertising firm in south-east London, although the brothers have not seen each other for more than nine years. Later, he described himself as a property developer.
Pearce's three-bedroomed house in Chiswick, west London, is split into three bedsits. He lived in the downstairs front room and rented out the three upstairs bedrooms.
One lodger, Graham Hunt, described him as "well educated and very knowledgeable about world events and the news".
Mr Hunt said: "He drinks heavily. He has some strange habits. Every morning he gets up early, about six o'clock, and cooks a roast joint of beef or lamb with roast potatoes and vegetables. It's like a normal person's Sunday lunch, but he has it for breakfast with a glass or two of red wine."
Much of Pearce's plotting took place in the greenhouse at the end of his garden where he would work until 1am.
Ten years ago, after 30 years of marriage, he separated from his wife, Maureen, 57, who lives in Welling, Kent.
His daughter, Nicola, 26, refused to believe her father was the Mardi Gra bomber. "My dad shops at Sainsbury's because he likes their food. He doesn't go there to bomb them," she said.
"He's a gentle man," she added. "He's not screwed up in the head at all."Reuse content