The Garda Representative Association says it's alarmed by reports that training and technology budgets will be cut to pay for last month's visit by US President Donald Trump.
It follows an internal Garda Report showing failings in the management of DNA testing - with a quarter of Gardai taking DNA samples without being properly trained.
“DNA profiling is one of the most powerful techniques in the identification of offenders and missing persons. It is an essential tool in crime investigation," said GRA Secretary General Pat Ennis.
“This is the Garda Siochána's own internal report highlighting under investment in training, ICT, staffing and facilities.
“We have been warning about this for years, yet now we see reports that the budget in these areas could be cut to pay for the visit of President Donald Trump and presumably Vice President Mike Pence, if he comes.
Irish people will be rightly annoyed if cases are not being detected or prosecuted due to the inadequate management of DNA testing.
"But to then hear that the cost of policing President Donald Trump's visit could prevent these systems weaknesses being addressed will cause a justifiable public outcry," he added.
“This should be a wake-up call for government that it needs to put money into training and ICT not cut it. The visit of President Trump will have to be paid for from some other source - not the Garda Siochana's budget.”