A Canadian man who sexually abused his 4-year-old daughter live on the Internet so another man could watch was sentenced Thursday to four years in prison.

An undercover detective who played a key role in catching the 35-year-old man criticized the judge's sentence as too lenient.

The father, whose name was not released to protect the identity of his daughter, was arrested in October 2006, just hours after he used a Webcam to expose his daughter to another man during a chat room conversation.

The father from St. Thomas, Ontario, pleaded guilty in October to seven criminal charges.

In sentencing him, Justice John McGarry called it a "gross case; a sickening case of breach of trust."

"Words cannot describe what is found in those pictures. They are of a three- and four-year-old girl being used by her father for his own sexual gratification," McGarry said.

Paul Krawczyk, the undercover detective who watched the live Internet assault, called the judge's sentence "sad."

"It's just four years. The child has to deal with this for the rest of her life, and not just the child, the mother of the child, the family members of the child," he told The Associated Press.

"The mom said it perfectly yesterday. She said it would be easier if the father was dead. Nobody ever thinks of the children in this," Krawczyk said.

The four-year sentence handed down Thursday takes into account time already served, which means the man will serve another 20 months and will then be on probation for three years.

In a victim impact statement read in court Wednesday by the prosecutor, the man's wife called him a "cruel person" and said she would rather have learned her husband was dead than discover the truth about his "despicable" behavior."

Defense lawyer Bob Upsdell told court Wednesday his client has been physically assaulted twice while behind bars, and has lost 130 pounds since his arrest.

Officials said the man is one of 82 men arrested worldwide as a result of a global police operation involving Internet child pornography, which began with the arrest of another Canadian man.