Method for detecting fraud when a device for capturing a print of a body part is being used, said device comprising a first transparent slide comprising an upper face on which a body part to be checked is placed, a light source comprising a plurality of LEDs lighting exclusively in the direction of the upper face, a screen which is opaque to light and located below the first transparent slide, a second transparent slide located below the opaque screen and an image sensor located below the second transparent slide, the two transparent slides, the opaque screen and the image sensor being parallel and the opaque screen comprising an array of holes which are intended to let light rays originating from the light source reach said image sensor, said light rays making it possible for the image sensor to generate an image of said print, each LED being configured so that each light ray produced by said LED has an angle with respect to the normal to the upper face which is smaller than a critical angle, characterized in that the method comprises: using said device to acquire a first print image with the body part to be checked being lit by the light source, referred to as the first type of lighting, such that the whole surface of the body part to be checked in contact with the transparent slide reflects light; using said device to acquire at least one second print image with the body part to be checked being lit by the light source, referred to as the second type of lighting, such that at least one LED is on; when a plurality of LEDs are on, said LEDs are at least distant by a predefined distance such that the sub-part of the finger D reflecting the light emitted by an LED is disjoint from any other sub-part of the finger D reflecting light lit by another LED; obtaining, for each second print image, information which is representative of a light level reemitted by the body part to be checked using said second print image and the first print image; and comparing said information with reference information which is representative of a light level reemitted by a real body part placed on the transparent slide in order to confirm that the body part to be checked is a real body part, said information which is representative of a light level reemitted by the body part to be checked comprises at least one curve representing a luminous intensity emitted by the body part and at least one curve of gradients of luminous intensity which is emitted by the body part in accordance with a distance to a centre of an area lit directly by the light source when the latter is lighting the body part according to the second type of lighting, each curve being obtained by taking into account only luminous intensities of pixels corresponding to ridges of the print of the body part, said pixels being identified using the first print image; or at least one curve representing normalized scalar products calculated between the first and the second print images and at least one curve representing gradients of normalized scalar products calculated between the first and the second print images, in accordance with a distance to a centre of an area lit directly by the light source when the latter is lighting the body part according to the second type of lighting. using said device to acquire a first print image with the body part to be checked being lit by the light source, referred to as the first type of lighting, such that the whole surface of the body part to be checked in contact with the transparent slide reflects light; using said device to acquire at least one second print image with the body part to be checked being lit by the light source, referred to as the second type of lighting, such that at least one LED is on; when a plurality of LEDs are on, said LEDs are at least distant by a predefined distance such that the sub-part of the finger D reflecting the light emitted by an LED is disjoint from any other sub-part of the finger D reflecting light lit by another LED; obtaining, for each second print image, information which is representative of a light level reemitted by the body part to be checked using said second print image and the first print image; and comparing said information with reference information which is representative of a light level reemitted by a real body part placed on the transparent slide in order to confirm that the body part to be checked is a real body part, said information which is representative of a light level reemitted by the body part to be checked comprises at least one curve representing a luminous intensity emitted by the body part and at least one curve of gradients of luminous intensity which is emitted by the body part in accordance with a distance to a centre of an area lit directly by the light source when the latter is lighting the body part according to the second type of lighting, each curve being obtained by taking into account only luminous intensities of pixels corresponding to ridges of the print of the body part, said pixels being identified using the first print image; or at least one curve representing normalized scalar products calculated between the first and the second print images and at least one curve representing gradients of normalized scalar products calculated between the first and the second print images, in accordance with a distance to a centre of an area lit directly by the light source when the latter is lighting the body part according to the second type of lighting.