CNN — While former NFL player Aaron Hernandez stood in court facing a first-degree murder charge this week, police were combing a condo he rented to search for evidence in the case against him.
Inside the condo, a district attorney said Thursday, detectives found ammunition for a .45-caliber weapon -- the same caliber weapon that investigators believe was used to shoot Odin Lloyd's last week.
Hernandez is accused of orchestrating the killing of Lloyd, a 27-year-old semipro football player whose body was found in an industrial park less than a mile from Hernandez's house. He has pleaded not guilty.
He's also being investigated in connection with an unsolved 2012 double homicide case in Boston, a law enforcement source close to the investigation told CNN.
The source gave no indication whether there was any connection between that investigation and Lloyd's killing, which drew national attention as Hernandez, a 23-year-old who was once one of the NFL's most promising rising stars, became a high-profile focus of the investigation.
In court, prosecutors have described witness accounts and surveillance footage that they argue solidifies their case against Hernandez.
But, according to First Assistant District Attorney Bill McCauley's arguments in court this week, one key piece of evidence apparently hasn't been found, the gun investigators believe was used to kill Lloyd.
Inside a Hummer registered to Hernandez parked in front of the condo he leased, McCauley said Thursday, investigators found a clip to a .45-caliber firearm.
Search jars neighborhood
By Thursday evening, the Hummer was no longer parked at the condominium complex in Franklin, Massachusetts.
Authorities towed it away after they scoured the area, neighbor Carol Bailey said.
The small condo Hernandez rented near the highway looks drastically different from Hernandez's large house with a plush, green lawn about 10 miles away in North Attleborough, where over the weekend police patrol cars filled the driveway as search dogs and detectives scoured the property.
At the condo complex about 20 minutes away, the police search Wednesday was a jarring sight, Bailey said, noting that she saw them using a dog to sniff for evidence and also carting in a ladder truck to get at the building's roof.
"We've never had the place crawling with cops," she said. "This is a very peaceful, quiet community. This doesn't happen here."
The retired biology professor said she never spoke directly with Hernandez, but she had seen him at the complex, wearing hooded sweatshirts in an apparent attempt to fly under the radar.
When police questioned her on Wednesday, Bailey said she told them she never saw anything suspicious going on in the condo next door.
"No suspicious activity, no girls, nothing other than just typical guy stuff. A little bit loud, a little bit of cigarette smoke, a little bit of, maybe pot," she said, "but nothing that you wouldn't expect from a bunch of guys."
Defense attorney: Hernandez is 'one of the best football players'
Details about the condo search first came to light on Thursday during a new hearing for Hernandez, who was pushing for authorities to release him on bail.
Hernandez's lawyers said their client had not obstructed the investigation, as prosecutors alleged, and was not a flight risk.
Defense attorney James Sultan said he wasn't asking for special treatment for his client, but stressed what he called Hernandez's professionalism and the athlete's stable home environment.
"Mr. Hernandez is not just a football player," he said, "but is one of the best football players in the United States of America."
He also noted that Hernandez was recovering from shoulder surgery and needed medical care. And he offered the use of electronic monitoring and house arrest as options.
But those arguments didn't convince Superior Court Judge Renee Dupuis.
"He also has the means to flee, and a bracelet just wouldn't keep him here, nor would $250,000," she said.
Hernandez tied to second murder investigation
Hernandez is now also being investigated in connection with a double homicide that occurred in Boston's South End in July 2012, a law enforcement source close to the investigation told CNN.
The source gave no indication whether there was any connection between that investigation and Hernandez's current murder charge.
What is known is that the Boston Police Department has located and impounded a silver SUV with Rhode Island registration that police have been trying to find for almost a year, which is linked to the scene of the double homicide, the source said.
Investigators said they believe Hernandez was renting the SUV at the time of those killings, the source said.
Rental car keys found in victim's pocket
On Wednesday, McCauley revealed that a rental car had been a key link allegedly tying Lloyd to Hernandez.
When investigators found Lloyd's body, McCauley said, the keys to a rental car registered to Hernandez were found inside his pocket.
Lloyd, 27, was a semipro football player who worked for a landscape company. His sister, Olivia Thibou, said last week that her brother was dating the sister of Hernandez's fiancee.
Lloyd and Hernandez were at a Boston nightclub together the night of June 14, she said.
Second arrest in homicide investigation
A second man has been arrested as part of the investigation into Lloyd's death, but authorities haven't provided details.
Carlos Ortiz, 27, was arrested Wednesday in Hernandez's hometown of Bristol, Connecticut. The arrest occurred in connection with the homicide investigation, a Connecticut state prosecutor said in a statement Thursday.
Ortiz was charged as a fugitive from justice, New Britain State's Attorney Brian Preleski said, indicating that documents had been sealed by court order.
In Massachusetts, a warrant for Ortiz's arrest says he faces a charge of possessing a firearm without a license, according to court documents obtained by CNN.
Ortiz spoke with investigators in Connecticut on Tuesday, according to an affidavit filed by a Massachusetts State Police trooper. In that interview, the affidavit says, Ortiz told police that he had been carrying a firearm in North Attleborough, Massachusetts, on June 17 -- the day investigators have said Lloyd was killed.
Details about Ortiz's alleged connection to the Lloyd case were not spelled out in the court documents CNN obtained.
He was being held on $150,000 bond in Hartford on Thursday.
It was not clear from court documents whether Ortiz has an attorney.
A 'model inmate'
During his first day in jail, Hernandez has been "polite and cooperative" and a "model inmate," Bristol County Sheriff Tom Hodgson said.
Hernandez was being held in the jail's medical unit, which is standard for someone who hasn't been incarcerated before, Hodgson said.
The former pro athlete showed "no apparent nervousness" in jail, Hodgson said, but he noted the difficulty of going from having thousands of people cheering for him to being "just a number."
While in the medical unit, Hernandez will be locked up for 23 hours a day, with a break for a shower and phone calls, the sheriff said.