LYNN – Police found a bloody mop in Ernesto Gonzalez’ apartment during a search they conducted this week in the wake of his son, Giovanni’s, disappearance last Sunday.The mop’s discovery Monday prompted police to apply for a search warrant Wednesday in an effort to retrieve any sign of blood from Gonzalez’ 2 Brightwood Terrace apartment.Essex County District Attorney Jonathan Blodgett said Friday night any time blood is found it is a concern but all involved in the search are still hoping Giovanni is alive.”Finding blood like we did is always a concern but at this point we do not know whose blood it is,” Blodgett said. “We will not know whose blood it is until the scientific results come back.”Blodgett said a door-to-door search as well as roadblocks would be used this weekend as the search for Giovanni continues. Blodgett said fliers would be handed out to people as investigators look for help locating the boy.”In addition to continuing the search efforts this weekend, work with the FBI will be ongoing as we try to put together a profile on Ernesto Gonzalez and construct what may have happened,” Blodgett said. “At this point we have reviewed almost all of the Transportation Safety Authority tape from Logan as well as Puerto Rico and nothing indicates that (Giovanni) left Boston or arrived in Puerto Rico.”The Monday search and Wednesday follow up took place even as police combed the city on foot and in the air this week for any sign of the missing boy.Giovanni Gonzalez, 5, has been missing since Sunday evening when his mother went to pick him up at his father’s downtown apartment building after dropping him off there on Aug. 15.After not being able to locate the boy or Gonzalez, she called police who questioned the father who, in turn, told them his son was not with him and that he had not seen the boy since the previous week.Gonzalez entered an innocent plea to a child endangerment charge Monday and is being held in the Essex County House of Correction.The mop was damp and partly stained reddish brown when investigators found it. A State Police chemist tested the mop using what the police search warrant application referred to as a “presumptive screening test for blood.””The presumptive screening test for blood resulted in a positive finding on both the mop and the cover of the pine cleaner,” State Trooper Brandon Arakelian stated in the search affidavit.In applying Monday for a warrant to search Gonzalez’ apartment for signs of blood and other bodily fluids, as well as hair and other items, Arakelian noted that police observed “an open cut and a bandaged finger” on Gonzalez’ left hand Sunday.”When asked how recent the injuries were, Gonzalez would not provide information about the injury,” the application stated.Police also took toys, two pairs of jeans, a belt, a child’s bicycle and helmet, lighter fluid, trash bags, a knife from a drawer, a knife retrieved from the apartment kitchen floor and other items including swabs from the kitchen and bathroom sink knobs following Monday’s search.State Police armed with a warrant also took a Dell computer and Nokia cell phone from Gonzalez’ apartment on Monday.In applying for the warrant, Trooper Michael Murphy wrote: “I know that it is not unusual for individuals involved in homicides, child abuse, and child endangerment-related cases to memorialize their victims’ abuse and/or deaths through audio and or video media for later viewing, for guilt relief or for enjoyment as trophies.”Daisy Colon continued holding out hope Friday her son will be found alive even as America’s Most Wanted posted Giovanni’s picture and information regarding his disappearance on its Web site.The Web site listed a Union Street clinic as one of the last places where father and son were seen Saturday afternoon. According to the Web site, Ernesto Gonzalez went to an appointment at the Lynn Behavioral Health Clinic on Union Street between 11 a.m. and 12:30 p.m. Saturday with Giovanni.The clinic is actually a dep