Ian Tuckley, 32, of the Special Air Services and who served with the Royal Welsh Regiment, admitted to downloading 6,000 child pornographic images, The Sun reported.
During his month-long trial at the Worcester Crown Court, he said he secretly harboured a sick desire for young girls and formed an obsession for child pornography. He said he could not help his sex addiction.
Tuckley subjected his first victim - now 19 - to a 13-year ordeal from the age of four. The second girl - now 10 - was abused between six and eight years of age.
He got one girl pregnant and forced her to have an abortion.
His partner in the crimes was his 40-year-old paramedic brother-in-law, who was also convicted for rape, indecent assault and administering a substance with intent.
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