"The emergency personnel will describe what transpired that night," the source says.
Court documents show Kevin Federline's attorney Mark Vincent Kaplan on Thursday subpoenaed the LAPD investigative report and the identity of the officers on the scene at Spears's four-hour custody standoff.
If the court decides on Monday to further suspend Spears's visitation rights, the singer may not see her sons until April, when the ex-couple's custody trial begins, Kaplan told PEOPLE.
As for whether Kaplan is amenable to Britney regaining visitation, he told PEOPLE on Monday, "It's a very short time since the events of Thursday and certainly I have seen nothing that has caused me to believe that there are dynamics in play now that will change my mind about the orders we sought."
Federline was temporarily granted sole legal and physical custody of sons, Preston, 2, and Jayden, 1, after Spears was hospitalized. Spears and Federline are not required to personally show in court on Monday.
'Medically Treatable Reason'?"At the next hearing, it's extremely unlikely Spears will get visitation restored to what she had," says family law attorney Lynn Soodik, who's not involved in the case. "One argument she could present is that the standoff was due to a medically treatable reason, and that she's now treating that problem."
"On the other hand, it's a terrible thing to keep children away from their mother," Soodik adds. "The courts will have to weigh that against the trauma of another possible standoff situation."
Even if Spears receives no custody after April's trial, "custody arrangements are always modifiable," Soodik says. "Since the kids are so young, that would just be the end of Round 1."
At the trial in April, a child custody evaluator will recommend to the court who the kids should be with, and any additional evidence regarding Federline's original request for primary physical custody.
"Until the kids turn 18, we can expect in years to come that both parties will be back in court," Soodik says.