(CNN)-- Something Odin Lloyd may have done or said didn't sit well with NFL player Aaron Hernandez, prosecutors say.
Two days later, they allege, the football player rounded up some friends and settled the score.
Lloyd's body was found at a Massachusetts gravel pit near Hernandez's North Attleborough home in mid-June, according to investigators. He was fatally shot with a .45 caliber firearm.
Hernandez faces premeditated murder charges and has pleaded not guilty. Prosecutors allege the former tight end with the New England Patriots orchestrated the hit and carried it out with another man.
The Patriots dismissed him from the team and ended his multimillion-dollar contract. Cell phone records and surveillance camera tapes will link him to the killing and retrace the final moments of Lloyd's life in the wee hours of Monday, June 17, the prosecution says.
And a trail of blue bubblegum colorfully shows Hernandez's path that night, according to prosecutors.
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But the defense says the evidence does not add up.
"It is a circumstantial case. It is not a strong case," defense attorney Michael Fee said. Massachusetts State Police said they are seeking another man as an "accessory after the fact."
Hernandez is also being investigated in connection with an unsolved 2012 double homicide case in Boston, a law enforcement source close to the investigation told CNN.
Over the weekend, Lloyd and Hernandez had a run-in, prosecutors allege.
They had met up at the popular Boston dance club, RumoR, according to Lloyd's sister, Olivia Thibou.
Lloyd, a semipro football player who also worked as a landscaper, was dating the sister of Hernandez' s fiancee.
In predawn hours Monday, Hernandez swung by Lloyd's home to pick him up in a rented silver Nissan Altima, prosecutors say. At some point, two other passengers ended up in the car with them.
They stopped at a gas station and made a purchase. But one that sticks out as evidence -- a pack of blue bubblegum.
Prosecutors say that cell phone towers nearby tracked the men's movements. Lloyd had his phone on and texted his sister at 3:23 a.m., very likely minutes before his death.
"NFL. Just so you know," he texted his sister to let her know who he was with.
About 3:25 a.m. -- two minutes after the message -- gunshots shattered the quiet night, according to witnesses.
Not five minutes passed before a surveillance camera captured video of Hernandez carrying a gun as he arrived back at his home, prosecutors say.
He was with two other people. Lloyd was not among them.
A murder weapon is usually a key piece of evidence in a homicide case, and investigators have not been able to turn one up.
But Hernandez at least once had a Glock .45, prosecutors say, entering a cell phone photo into evidence of him posing in the mirror with it.
And police have seized .45 caliber ammunition and an ammunition magazine that were in a Hummer SUV he drove and a condo he rented.
Hernandez and the other two later took the car back to the rental company.
There, the defendant offered an attendant a piece of blue Bubblicious, prosecutors say.
What appeared to be a piece of chewed blue gum was left lying inside the vehicle, prosecutors say. Next to it was a fired.45-caliber casing.
It matches the empty shells Investigators recovered near Lloyd's body, prosecutors say.
If that gum was in Hernandez's mouth, DNA tests will connect him to the casings, prosecutors say.
When investigators inspected Lloyd's body, they found keys in his pockets to a rental car registered in Hernandez's name.
The former pro football player awaits trial in a county jail, after the judge denied him bail. He has been "polite and cooperative" the sheriff says. He seems at ease.
But Hernandez has had some difficulty with one thing, Bristol County Sheriff Tom Hodgson said.
Trading in the glory of jersey number 81 for the impersonal feel of a prisoner's serial number.