Family, friends and supporters gathered at the Temple Beth Am in Pinecrest, Florida to say goodbye to Steven Sotloff, the American journalist who was beheaded by Islamic State militants earlier this week.

Almost 1,000 people attended the public memorial, which was held Friday afternoon at the temple where Sotloff attended elementary school.

Sotloff, who freelanced for Time and Foreign Policy magazines, disappeared while reporting overseas in Syria in August 2013.

On Monday, the extreme Iraqi terrorist group known as the Islamic State in Iraq and Syria, or ISIS released a video that recorded Sotloff being beheaded. A masked militant also addressed President Barack Obama in the video, saying, "Just as your missiles continue to strike our people, our knife will continue to strike the necks of your people."

During his memorial service, a cousin of the slain 31-year-old journalist read a letter that Sotloff managed to smuggle out of captivity through a former cell mate back.

"Please know I'm OK," said Sotloff in the letter, which was written in May, according to the Miami Herald. "Live your life to the fullest and fight to be happy....

"Everyone has two lives. The second one begins when you realize you only have one."

"Is there a sorrow greater than this?" Sotloff's rabbi, Terry Bookman, said at the service "We grieve for what may have been... for hopes thwarted... for challenges still unmet."

He went on to say: "Though we are aware of the geopolitical significance of his death, let us not forget there is a grieving family devastated by their loss, and let this service begin their healing. Steven was taken from us because of what he represented: freedom and the equality of all people."

"I have lost my son and best friend, but I know his passing will change the world," said his father, Arthur, at the gathering, reports NBC News. "I want to speak from my heart but my heart is broken."

Sotloff's father added that "I know that his passing will change the world. He's in God's arms now. He's not suffering anymore."