Manassas - A Virginia man convicted of murdering his 15-month-old-son to collect on life insurance was sentenced on Tuesday to life in prison without parole.Joaquin Rams of Manassas was convicted earlier this year in the 2012 death of his son Prince.Rams had taken out more than $500 000 in life insurance on Prince in the months before his death. The boy died during an unsupervised visit ordered by a Maryland judge over the objections of Prince's mother, who said she feared for her child's safety. Prince died on just the fourth unsupervised visit Rams had with his son.Obtaining a conviction in Prince's death was a challenge for prosecutors, and took several years of legal wrangling. The medical examiner who conducted the autopsy on Prince concluded that he drowned, but later the state's chief medical examiner overruled that finding and changed the cause of death to undetermined.That opened the door for defence lawyers to argue that Prince died of natural causes, citing a pattern of fever-induced seizures that had been documented during Prince's short life. The murder trial became in large part a battle of medical experts as to whether febrile seizures could be fatal.'A pathetic excuse for a human'Judge Randy Bellows, who convicted Rams after he waived his right to a jury trial, wrote a meticulous 62-page opinion detailing why the defence argument that Prince died of natural causes made no sense in light of the specific circumstances of his death.Rams, who maintains his innocence, filed a request seeking to avoid attending Tuesday's sentencing hearing. But Bellows ordered him to attend, giving Prince's mother, Hera McLeod, and maternal grandparents the opportunity to give victim-impact statements in Rams' presence.McLeod said she can't help but think of Prince's death."I know it was painful. I know he was scared. I have to live with the fact that I was unable to protect him from this monster."She then turned directly to Rams, who looked away, twitched and sighed as McLeod called him "a pathetic excuse for a human.""I don't forgive you."Rams remained silent when he was offered an opportunity to speak at Tuesday's hearing.Linked to more deathsRams was convicted of capital murder, but prosecutors agreed not to pursue a death penalty under an unusual exchange in which the defence waived its right to a jury trial. While Virginia law says a capital-murder conviction requires a sentence of life without parole, Rams' lawyer, Christopher Leibig, asked the judge to suspend part of that sentence and provide some option for Rams to be released.Bellows rejected that request, calling the murder "cold, calculating and callous in its nature, and shattering in its impact."His lawyers are planning to appeal.Prosecutors also believe Rams is responsible for the deaths of his ex-girlfriend, Shawn Mason, and his mother, Alma Collins. In Mason's death, prosecutors say Rams believed he would be the beneficiary of a life insurance policy. In Collins' death, Rams did in fact collect on a life insurance policy.It is unclear whether Rams will ever face charges in those two deaths. Commonwealth's Attorney Paul Ebert said the cases remain open and he can pursue charges if needed.Shawn Mason's mother, Sheryl Mason, said after Tuesday's hearing that she is satisfied with the life sentence and is no longer pushing for a separate trial in Shawn Mason's death."I know who is responsible for Shawn's death," she said after the hearing. "For me, this is justice for Shawn as well."