Spears and Federline
INF; Jamie McCarthy/WireImage
08/19/2007 at 02:00 PM EDT
While Kevin Federline
parties in Vegas
, his defense team has struck again, delivering a subpoena to the rehabilitation facility attended by his ex Britney Spears
Federline's lawyer, Mark Vincent Kaplan, confirms that Promises Treatment Center was served with a subpoena Saturday morning, saying, "An executive administrator from Promises rehab facility was served with a subpoena."
This is the fourth subpoena doled out by the Federline team in the singer's increasingly high-profile custody battle
. Earlier in the week, Spears's former assistant Shannon Funk
, bodyguard Daimon Shippen
and pal Alli Sims
were all served with legal papers.
"Kevin and his attorneys Mark Vincent Kaplan and James Simon are on a mission," says a source familiar with the proceedings. "They are pursuing all relevant evidence from every potential source and every available witness."
A spokesperson from Promises refused to comment, saying: "This is a confidential facility and we cannot comment."
The pop star spent a month at Promises and was released on March 21. Her manager at the time said she was "successfully" released.
According to Pepperdine University law professor Steven M. Cron, the Federline camp is clearly seeing how Spears took to the Promises stint.
"Strategically I don't think they are concerned with the treatment, but how she responded to that treatment," says Cron. "Specifically, if she participated as she was supposed to. Did she have a positive attitude, did she complete it successfully. Or was she a screw up?"
With reporting by JENNIFER GARCIA