In late March, Fox News reported on its website that $3 million of private money raised by the New Tribes Mission (NTM), the organization which sent the Burnham’s on their religious mission to the southern Philippines, was paid to the Abu Sayyaf for the safe return of the missionary couple in time for the Easter holiday.
A report in the Washington Times on April 11 said that the correct figure was $300,000, citing “two senior administration officials” who said that the payment was made “through a third party in a bid to gain the release of two Americans.” (4/11/02, The Washington Times)
The next day, a Reuters story reported that “A U.S. official told Reuters in Washington that the ransom money was handed over to an intermediary of the Abu Sayyaf several weeks ago and confirmed television reports that the government helped arrange the payment.” (4/12/02, Reuters)
The Reuters report also said that residents of Basilan had confirmed that “the reports of the payment of $300,000 for the release of two Americans missionaries were true.” (4/12/02, Reuters)
I'm not sure that this is analogous to the DC sniper case, though. These were private funds, not public money, and this ransom was paid after a year, not as an immediate response. (The immediate payment of ransom would be far worse in terms of encouraging future kidnappings.) And I'm sure that this is not the first time that police or other government officials have cooperated with private individuals who are willing to pay ransom to try to save a kidnapped person.
On the other hand, you can see how poorly this worked for the Burnhams. This experience wouldn't encourage the payment of ransom in other cases.