Vice President Joe Biden on Saturday eulogized slain NYPD officer Rafael Ramos, who was shot dead "execution style" by a man who posted on social media that he wanted revenge for the deaths of Michael Brown and Eric Garner."The time will come when Rafael's memory will bring a smile to your lips before a tear to your eyes," Biden told Ramos' family. "I speak for the whole nation when I say our hearts ache for you."The funeral, which was held in Queens, was attended by thousands of police officers and city officials, including New York Gov. Andrew Cuomo (D), New York City Police Commissioner Bill Bratton and Mayor Bill de Blasio. Police union officials have spoken critically of President Barack Obama and de Blasio for delivering remarks they saw as contributing to a climate of mistrust toward police in the wake of national protests over the deaths of unarmed black men at the hands of police.According to CNN, several officers booed when de Blasio arrived to the service, and some protest signs were shown. Photos shared on social media also showed police officers turning their backs on the mayor. NOW: Showing defiance against #NYC Mayor #Deblasio, 1,000's of police turn their backs, face away from him. @NECN pic.twitter.com/x2FdEwapgg' Justin Michaels (@JMichaelsNews) December 27, 2014During his remarks, de Blasio called Ramos a "hero" and praised the police department."Our hearts are aching today. I feel it physically, I feel it deeply," de Blasio said. "New York City has lost a hero, a remarkable man because of the depth of this commitment to those all around him. On behalf of all of us, I extend my condolences. I extend my condolences to the NYPD that is hurting so deeply right now, as their families feel loss as well."Funeral plans haven't yet been announced for Ramos' partner, Officer Wenjian Liu, who was also shot dead last week. Click here to read full news..